Telling Tails
by Garrae
Summary: Immediately following their twins' appalling revelations to Jim in Toddler Taming, the Caskett Cats need to bring some others in on the secret. Matters do not proceed precisely as planned. More insanity in the Cool for Cats Universe. Caskett Cats #10.
1. Chapter 1

**Chapter 1**

"What are we going to do now?" Beckett asks despairingly, after Jim has departed, still completely discombobulated by the discoveries about his daughter and grandchildren. They'd offered to get him a car, but he'd said he thought he'd rather walk, to clear his head.

Beckett's not sure what head-clearing is required, other than a brain wipe, and even that would only last till the next time. Her terrible twosome haven't stopped shifting for a moment. Petra, always more determined and focused, is practising hard, and the sneezing is already diminishing in volume and vigour. This is helpful, in one way, since neither parent is _that_ fond of constantly wiping snotty noses clean and mucus away. (The twins are also not fond of nose-wiping, but they don't get a choice in the matter.)

"I don't know," Castle replies, also looking at the twins. "Did you ever find anything that stopped you changing?"

"I wasn't looking, but nothing." She slumps. Castle comes and hugs her. "This is awful. We were going to start daycare, but that's out the window. We can hardly keep them inside 24/7, but what happens if you take them to the playground and suddenly there's two cats? Not good for the friendship groups."

"The children would love it."

"The other parents wouldn't," Beckett says crossly. "Just because you'd have loved it, doesn't mean anyone else would."

Petra discovers that being a toddler means that she can steal all the blocks from David-panther, who caterwauls loudly in complaint when he finds he can't steal them back with paws. He changes. Petra becomes a panther and swats his toddler form. The wails get louder.

"Stop that, Petra!" Beckett says. "You share the blocks." Petra turns her back. Beckett picks her up to eye level and stares her down. "You share, or time-out." Petra shares, recognising a stronger will than hers.

"That's not the worst of it," Castle points out gloomily, as Beckett returns to their joint floor cushion and nestles in again.

"Huh?"

"Mother, Alexis, Espo, Ryan, Lanie…"

"Oh, _sh-oot_!" There is a swift change of word there. "We can't never have them round."

"I can't not take the twins into the precinct to see you, either."

"Oh, God." Beckett considers the likely reaction of Captain Gates to two cubs, and does not find it good. She buries her face in Castle's shoulder. He pats her.

After a few moments, Beckett emerges. "I have an idea," she says gloomily.

"If it arrives in that tone, it's a bad idea," Castle points out. "Or a good idea that you hate."

"Yeah, but…like I said, we can't put the twins in an isolation cell." Though some days, when they are particularly badly behaved, it's a very appealing idea.

"We could take them up to the cabin," Castle suggests, "and teach them never to change without us telling them to."

"Castle," Beckett says with considerable exasperation, "even if they weren't _your_ children" – he squawks – "toddlers have the attention span of a doped butterfly."

"I have plenty of attention span," Castle argues, and then drops his voice, "as you found out last night."

Beckett colours delicately. Castle had certainly demonstrated considerable and prolonged focus. She, on the other hand, had shortly been unable to focus at all.

"Even if we got it through Petra's head, David wouldn't remember past the first time he thought doing it was a good plan in his mind." She smirks nastily. "He's really very like you."

Castle grouses under his breath. Beckett sighs, still cuddled in. Astonishingly, the twins are playing co-operatively. That might, of course, be because both their parents are watching. She sighs again.

"Going up to the cabin's a good idea anyway. I've got some vacation days to take." She nods decisively. "Let's do that, too."

"Too?"

"Yeah." She returns to her deep gloom. "I never, ever wanted to do this, but – I think we need to tell your family and the team. And Lanie." She pauses. "And – er – Gates."

Castle goggles at her, boggled. This swiftly changes to consternation. "Beckett?" he gleeps. " _All_ of them?"

"Uh-huh. And then we threaten them. Though if your mother ever mentioned it everyone would put it down to too much wine."

"True," Castle says, "but just a little mean."

He ponders for a time. While he does so, the twins are empirically testing the relative advantages of each form over a range of activities, which, as ever, rapidly descends into squabbling noisily and then fighting. Naturally, Petra is the first to discover that paws and claws are far better than hands for fighting, which equally naturally and much more rapidly lands her in time-out with a very stern lecture while David is being daubed with Neosporin and cuddled and fussed over until he stops wailing loudly.

"Oh, God," Beckett says wearily. "Is this our life now? Refereeing and para-medic-ing? Child Services are going to have a field day."

"If Petra wasn't just like her mother…" Castle says provocatively in revenge for Beckett's earlier comments on David's similarity to his father. He notices Beckett's distress. "Don't worry. Children do hit and fight. We just have to keep heading it off and dealing with it."

"Or add Petra to the precinct SWAT team," Beckett suggests. Castle snickers.

"Anyway," he says, letting David down from his arms and watching him toddle back to the blocks and toys, "you think we should tell Mother, Alexis and the boys."

"And Lanie" –

"Yes, okay, but why _Gates_?"

"Protection."

"Uh?"

"She can – er – leave out a few details, if necessary."

"Are you suggesting that our twins might get into trouble?"

"No," Beckett snips, "I'm suggesting that if they take after you they _will_ get into trouble."

Castle fakes a wounded look. "Mean."

She plants a peck on his cheek. "There. All better."

"Kiss too, mama!" David demands, and gets one.

"Me!" Petra says, and also gets one. Castle gathers both twins into a bear hug and tickles them till they squeak. They happily go back to their toys and shortly there is noise and banging. Helpfully, the loft is soundproofed.

"I guess you've got some ideas about the order of – er – introductions?"

"Yeah. Gates first. We'll need her to whitewash any issues with the boys, and possibly Lanie. And she can arrest anyone else who's – er – difficult about it."

"So can you."

"Yeah, but it's better if it's not their parent."

"And then? After Gates?"

"Don't know. Seems a bit unfair that my dad knows and your family doesn't, but it's easier to keep my dad quiet. He's an attorney. He's used to confidentiality."

"Much as I hate to agree with that, my family is not used to discretion or filters."

"But she is a good grandmother."

"Gramma come," Petra instructs.

" _My_ Gramma," David argues.

"NO! Mine!"

"Mine!"

"Grandma is for both of you. Share nicely."

"NO!" the twins yell in unison.

Their parents sigh. "Time out?"

"Guess so."

The twins separated, or possibly caged, for a moment or two, Castle and Beckett consider the unhappy necessities of the next few days.

"Gates, then Alexis, then Mother, then the rest, all at once."

"Yeah. Ugh," Beckett agrees, sunk in deepest gloom.

Gloom is not relieved by the twins being returned to the family room and smothering her in sticky fingerprints, scattering small blocks on which she will undoubtedly stand late at night and have to suppress her swearing, and implanting sloppy, soggy kisses and hugs. Sweet as it is, there's only one person with whom she _wants_ to exchange bodily fluids, and he is not two. Toddler affections have no discretion at all.

"Monday is not going to be any fun," she grouses.

"Monday?"

"No point delaying. Erm…. I'll give you a call when I've looked at her schedule so we can deal with Gates. I think you should bring the twins… they're cute, and she quite likes them."

"As much as she likes anyone," Castle humphs.

"Just because she doesn't like you…" Beckett notes, idly. Castle growls. "C'mon. Let's get the terrorists fed, bathed, and into bed." Suddenly she grins widely. "If they're not synced any more, I can be Onyx whenever I like!" Castle's answering grin lights up the room.

* * *

The next day, Beckett sneaks a look at Gates's schedule and discovers that she is free, or at least does not have meetings with 1PP or any other important personages, at the end of Monday.

This is good, and even better, the boys will have gone out interviewing and will be missing until the next day. It means that Castle and the twins can leave with alacrity when it inevitably all goes horribly wrong. Gates's reaction will probably be rather less reasonable than that of Dr Maine, and a quick escape may be required. There will be considerable acerbity. Gates is not a people person, and it seems entirely reasonable to assume that she is also unlikely to be a pet person. Even if she were, Beckett has yet to meet _anyone_ who claims to be a panther person.

At five on Monday, Castle texts to say that they're about to come up. Beckett tells him to make it really, really quick, before anything more can go wrong, and then, when they arrive, astonishingly all human, knocks extremely rapidly and trepidatiously on Gates's door before anything dreadful can happen.

"Yes, Detective Beckett?" Gates says, regarding her with a chilly stare which has not abated in almost four years of working together. For a given value of _working together_ , that is, which does not encompass friendship, though it has become mutually respectful.

"Er, we" – Gates raises an eyebrow at the unexpected sight of Castle and the toddlers within her sanctum – "need to talk to you, sir. Privately, sir." The eyebrow lifts further as Castle shuts the door, and puts both twins down. This, happily, removes them from Gates's immediate field of vision.

"If you wished to tender your resignation, Detective Beckett, I assure you that you did not need either Mr Castle or your children to protect you. I should, of course, be extremely disappointed."

Beckett's jaw drops, on account of both statements. "No sir. No. Not resigning. Um… Castle and the twins aren't here to protect me."

"And one assumes that you are not pregnant, either, since that would not require your entourage."

"No!" Beckett emits, horrified.

"So why have you planned this expedition? Surely even Mr Castle's offspring do not require me to bring down the force of the law upon them at two years old?"

Beckett twists her hands. "Sir, um – Castle, close the blinds, please" –

"What?" snaps Gates.

"Um… I… we… have a genetic condition."

Gates suddenly acquires a small hint of concern. "You do? You and the children?"

Beckett looks down. David is still a toddler. Petra is not, and worse, is sneaking stealthily towards Gates's ankles. She'd better get this out quickly.

"All four of us. And… er… with the twins getting older it's beginning to be difficult to hide it."

"There is no medical condition on your personnel record, Detective," Gates points out coldly.

Petra takes another prowling step closer. Captain Gates's shoes have a neat tassel on them, which is swaying enticingly.

"No. Um… Sir, I'm a shapeshifter. We all are. And the twins aren't synced to me any more so we can't hide it."

Gates stares at them. "Are you _insane_ , Detective?" she emits, freezingly.

"She sounds just like Dr Maine," Castle points out.

"A doctor?" Gates forces out in a strangled gasp. "A doctor helps you maintain this delusion?"

"Um… I think you'd better move your feet," Castle says to Gates, spotting Petra.

"I think it would be better if you moved yours," Gates snaps. "Right out of my office – Holy Mary Mother of God!"

Beckett, deciding to slice through the inevitable outrage and disbelief, is now Beckett-panther. Petra is one scant baby pounce away from Gates's shoes when Beckett growls and she comes skittering back. Castle picks her up. Gates appears to be praying. So far she has prayed to the Holy Trinity, the Twelve Apostles and more saints than Beckett had known existed. She'd never realised that Gates was religious. Then again, a full size panther appearing in your office could make anyone religious.

"Captain Gates," Castle says, "please would you open your eyes? This is Petra. You've seen her before. From a distance, admittedly, because it's not like you're really very keen on any of us or anyone else so we didn't bother you but" –

"Be silent, Mr Castle."

Petra, taking offence at the tone, attempts a growl, and receives in return an icy glare. She squirms and wriggles in Castle's arms and turns back to a toddler. Fully occupied with Petra, Castle fails to notice David toddling over to Captain Gates. David, unlike Petra, regards the world as populated by friends whom he has not yet met, despite all too frequent rebuffs. Beckett, who is regarding Captain Gates's frozen face with abject terror despite her claws and sharp teeth, likewise fails to notice the imminence of disaster in the form of David.

He plants both, undoubtedly sticky, hands on Gates's well cut suit, and looks adorably up at her. "H'lo," he says. "Mama a cat." Gates directs her glare at him. David resorts to measures which worked on his grandfather, and becomes a very cute black kitten, with bright blue eyes. He leaps up into Gates's lap. Instead of the petting he clearly expects, Gates picks him up by the scruff of the neck, regards him beadily, and places him on the desk in front of her. He extends a tentative paw in her direction.

"Sit still," she commands. David becomes petrified.

"Wow!" Castle says. "Even Beckett can't do that. Have you thought of hiring out as a nanny? I'd pay a fortune for you" –

"Mr Castle. Just over four years ago, against my better judgement and wishes, I took over this precinct, rather than remaining with Internal Affairs, following the death of Captain Montgomery. Since then, also against my better judgement, and _certainly_ against my wishes, you were permitted to return to shadowing Detective Beckett. I have always considered this to be a mistake, although you have to some minor degree proven useful. Your usefulness, however, is entirely dwarfed by your capability to cause complete chaos." She takes a very chilly breath, and continues before he can protest. "Now I find that my senior detective is a supernatural impossibility, and, as ever, you are at the centre of events."

"Why does everyone think I did it?" Castle complains.

"Dada did it," Petra says happily. Gates regards her with disfavour. So does Castle.

"It wasn't me," Castle says plaintively.

"It wasn't," Beckett says, changing back. "I was a cat long before I ever joined the Academy."

This does not appear to improve Gates's mood.

"My precinct does not require supernatural assistance."

"Are you firing me, sir?" Beckett enquires tightly. "What reason will you give 1PP – or the court, when I sue?"

"No, I am not firing you – I said _stay still_ ," she directs at David, who squeaks and cowers.

"Dada did it," Petra says again.

"Shush!" Beckett tells her.

"I note that your children are as ill-disciplined as their father," Gates says, "although they, at least, have the excuse of childhood."

"My children," Beckett snaps, heedless of rank, "are a lot better behaved than you've just demonstrated."

"Nasty lady," Petra says.

" _Quiet_ ," Beckett tells her. "Say sorry. You were rude."

Petra looks very like she's about to say _no_. Then she regards her mother's face. "So'y," she says.

"As am I, Detective. I should not have said that."

Beckett thinks she hears _in front of any of you_ , and lets it go.

"So. Yet again, Detective, you and Mr Castle have presented me with a problem. Explain why I should be concerned with any of this?"

"Until Saturday, sir, the twins were synchronised with me. If I was human, so were they."

Gates regards the kitten on her desk and the toddler in Castle's arms with some irritation. "I see. Clearly this is no longer the case." David tries a surreptitious prowl towards an interesting figurine. "Please remove your kitten from my desk. Your husband destroying one of my collection of rare dolls is quite enough."

Petra looks like she's thinking of saying _Dada did it_ again, and receives another searing glare from her mother.

Beckett removes David from temptation, with an expression very similar to that she uses when trying to stop Castle doing something dumb. Or heroic, which often seems to be the same thing.

"We thought," she carries on, "that informing some carefully selected people might help us manage the situation."

"Should I be flattered?" Gates enquires. She does not sound flattered. Appalled might just about cover it. "I can think of no reason to involve me in this" – she searches for a word – "debacle. _My_ precinct should be run in an orderly fashion, which does not involve children or shapeshifting. I would prefer it did not involve Mr Castle, either." The accent on _shapeshifting_ conveys absolute abhorrence.

"Sir, given the choice I don't think any of us would have been a shapeshifter."

"I would," Castle says. "It's totally cool."

"I have no doubt that _you_ would think so. However, your preferences are entirely irrelevant to this discussion." Castle subsides, squashed.

"Sir, the fact is, we _are_. You might not like it" –

"I don't. Is that not obvious?" –

"but it's true. And we need your help. Or at least your silence, because" –

"Because you can't afford to let this be known. Tell me, Detective, how long has this been going on?"

"Me? Um… since I was nineteen."

Gates goggles. "You have been a panther since nineteen?"

"I didn't realise till I was twenty," Beckett says, not that this appears to help anything. "And no-one at all knew until six years ago, when Castle worked it out."

Castle preens. Gates does not look impressed. "That may explain your children," she says coldly, "who may indeed deserve some protection. It does not explain Mr Castle."

"She changed me. She bit me and then" –

"Shut up, Castle."

"Biting naughty," Petra says, in saintly tones which bear no resemblance to her personality, or indeed her distressingly frequent actions.

"Shush!"

David wriggles in Beckett's grip and becomes a toddler. Gates emits a squeak, then recovers. She raises her eyes to Heaven.

"You thought it was a good idea to change Mr Castle," she says flatly.

"I asked!" he says.

"You whined," Beckett says tartly.

"Be _quiet_ ," Gates says, and all four of them are. "So. All four of you are shapeshifters, which, until today, I was unaware had existence outside of a niche genre of so-called literature. I assume, from the evidence of the last few moments, that you are all both panther and cat. And, for some reason which you have yet to disclose, you believe that I am both in a position to assist you and that I would actually do so."

She fixes them with a glare. "I do not appreciate you springing this upon me. However, I will not dismiss it out of hand. I shall consider. When I have finished, I will let you know. In the meantime, do not bring your children to the precinct. Mr Castle, you and the twins may leave." That is most definitely an order. "Detective Beckett, remain."

Castle casts her a look of sympathy, collects both his toddlers and achieves the elevator in nothing flat, before anything awful can occur. Beckett quivers.

* * *

 _Thank you to all readers and reviewers._

 _Yes, this is another insane instalment in the Cool for Cats universe, as if that weren't perfectly obvious. This is the responsibility and fault of a combination of Shutterbug5264 and BigKahuna, who each wanted to know what would happen when the twins weren't synced any more. All complaints of contagious craziness should be directed to them._

 _13 chapters. Sun/Tue/Thu schedule, unless otherwise advised._


	2. Chapter 2

**Chapter 2**

"Close the door," Gates orders: Castle having left it ajar in his haste to depart. Beckett does so, nervously. She anticipates a dressing-down from which Attila the Hun could have learnt. Gates has not, so far, been impressed.

"Now, Detective Beckett," Gates growls, "the truth, please." Beckett gleeps, which fails to improve Gates's expression. "Who else is aware of your… condition?"

"Er… Dr Maine – my ob-gyn who's the twins' doctor" –

"I recall her."

"Detective O'Leary" – Gates raises her eyebrows questioningly – "At Central Park. The really big guy?" The eyebrows lower and recognition takes the place of query. "And my dad. And that's only because the twins desync'd at the weekend when he was visiting." There is a trace of irritation in her voice.

"I see," Gates says, no clue to what she is thinking in her voice. "And who else were you planning to inform?"

"Castle's mother and daughter, Ryan and Espo, and ME Parrish."

"They don't know?" Gates emits, with the first real emotion she has shown since surmounting her initial shock and terror.

"Until Saturday, nobody but Dr Maine and O'Leary knew. Nobody else was _going_ to know," Beckett says crossly. "It's not the sort of thing you tell people over tea and cookies, is it?"

Gates regards her with a basilisk stare. "Did you not consider that it might be a relevant fact relating to your employment?"

"No. I investigate with a gun and shield, not claws and teeth."

"Hm." Gates relapses into silence. Beckett remains standing. "Why is it, Detective Beckett, that whenever something untoward occurs, you and Mr Castle are invariably at the centre of events?"

"I don't know, sir," Beckett says woodenly.

"Hm." Beckett awaits verbal dismemberment. "It is as well for you, Detective Beckett, that I have no objection to cats, as long as they do not disrupt my precinct in a way which would force me to notice them. In fact, I am quite fond of cats."

 _Uh, what?_

"I would not, for example, feel it necessary to notice any reports of big cats being spotted in Manhattan, provided there was no physical evidence." Beckett gapes. "Indeed, I might consider that any such reports stemmed from an over-indulgence in alcohol or prohibited substances, since it would be quite ridiculous for anyone – except, of course, Mr Castle, whose credulity remains unequalled – to believe in shapeshifters, or indeed panthers in Manhattan."

"Urg?" Beckett chokes out.

"Now, let us discuss practicalities."

"Practicalities?"

"Yes, Detective, _practicalities_. Presumably that is why you have told me your secret?"

"Yes…"

"Well? Have you not thought of what you want to achieve?"

"Just… well, help us keep it quiet. And try not to notice the twins."

"Mm. That is not a particularly well thought out strategy, Detective. You will have to do better than that. You may report to me in a week with a better plan. In the interim, I should be grateful if you would invite me to your apartment so that I can understand the situation better. You may arrange for me to observe your three forms then. I shall be free on Thursday. You may continue with your plan of informing those persons to whom you intended to disclose your secret. Please try to avoid any unfortunate events before my visit."

Beckett gapes, utterly speechless. Gates tuts.

"Dismissed, Detective."

Beckett returns to her desk, completes her shift, and departs; so completely flabbergasted by Gates's behaviour that she barely remembers to look both ways at the crosswalk and has her hair ruffled by a speeding truck. Fortunately she gets her head back in the game before she starts her car.

"Gates is coming round on Thursday night," she says to Castle, who promptly pours them each a very large glass of wine. The twins have been put to bed. Whether they will stay there, or indeed stay human, remains to be seen. Beckett is not hopeful. Castle, as ever, is more optimistic; in which case, Beckett points out, he can deal with any night-time excursions, miaowing, or growls. The stairgate is firmly shut.

"Thursday?" he squeaks. "What? Why? You _invited_ her?"

"Don't be dumb, of course I didn't. She invited herself. She said she had no objection to cats" –

"How flattering," Castle says dryly –

"and then said that anyone reporting big cats would be drunk or doped" –

"That's a bit more useful" –

"demanded a _plan_ from me within a week about what we want her to help us achieve" –

"Glurp?"

"and told me to invite her on Thursday so she can – quote – observe the three forms."

"Gleep."

"Yeah," Beckett says dispiritedly. "As if life wasn't complicated enough." She takes a very large gulp of her wine. "Well, I'm not tidying up for her."

"We never do anyway. That's what the cleaning service is for. Er - do I have to cook?"

"No. Maybe some chips."

"Wine?"

"Shouldn't think Gates ever does anything that pleasant."

"Not for her, for us," Castle says.

"Definitely. And possibly for the twins, to sedate them."

Castle snickers. "Wouldn't Benadryl do better than wasting our best wine on toddlers?"

Beckett tries for an eye-roll and ends up with a snigger. "Not a good plan. We'd be arrested." She pauses. "Probably. Until the arresting officer met Petra. Then he'd give her back – fast. Anyway. Gates is coming on Thursday. Ugh."

"Never mind Gates. What are we going to do about Mother and Alexis?" He pours some more wine. The first glass has mysteriously disappeared. "We said separately, but maybe it would be better to do it together?"

"You think? Won't that just let them both have joint hysterics?"

"Alexis won't have hysterics. She's sensible." Beckett looks sceptical. "She is!"

"Usually. This might be a step too far."

"No, no. And it would get it over with."

"Yeah…" says Beckett thoughtfully. Getting it over with is definitely a good plan. "If 'twere done when 'tis done, 'twere well it were done quickly."

"I really hope you're not going to turn into Lady Macbeth and start forcing me to stab people?"

"Depends on Thursday evening. I might want you to stab Gates for me."

Castle looks quizzically at her, and then wickedly. "I can think of much better forms of – hm – stabbing," he says.

"Can you?" Beckett says, seductively. "I can think of some other things to do. Starting with this," and she suddenly becomes Onyx. Castle instantly follows her into his panther, and stalks her round the family room until she lets him catch her (up at the cabin she'll make him work for that, and he'll have to catch her for real, but not here. Especially if she wants to be caught) and pin her under a huge paw; always gentle, always careful when she's the much smaller Onyx.

She snuggles in between his front paws, tucked against his neck where his head lies on the floor cushion, so close together that an observer certainly couldn't have told where her fur stops and his begins. His forepaw curves around her, holding her close, nuzzling her neck. She wriggles even closer, and nips gently, a suggestion, not a command (as her panther, she would be much more assertive). Castle traps her tidily between two massive forelegs, and then changes sneakily back to human with her still caught. He pets her, massaging down her spine and then fondling around her ears. Now, he knows exactly what that does for her. She purrs, and pushes her head into his hands. He plays for a little longer, and then picks her up, puts her against his shoulder, and murmurs sleepily into her ear, "Change back, love."

As she does, she's clasped against his chest, head still on his broad shoulder, and perfectly positioned to enjoy his matching arousal. They press together, still happily entwined on the floor cushions, and then Castle sits, stands, pulls Beckett with him, and (since the twins haven't emitted a single peep since bedtime) tugs her to the bedroom.

* * *

"Beckett."

"It's me. Mother and Alexis will come after the twins have had dinner tonight. So around six. Will you be home?"

Beckett _wants_ to say _No, we caught a case_. Except they haven't caught a case, and lying is not a good thing to do. Very tempting, but wrong.

"Yes," she replies, dispiritedly. She's never very keen on Martha's theatrical histrionics, and she expects that there will be a goodly number of those. She's also not at all convinced that Alexis will react well, despite Castle's optimism. Surely even Alexis has a breaking point? Her own father's reactions don't really help Beckett to anything other than deepest, darkest pessimism.

"I'll be home about five-thirty. Nothing but cold cases and paperwork." And she hasn't thought of a plan, either. She has achieved an invitation to Ryan (without Jenny or Sarah Grace), Esposito and Lanie for Wednesday.

At five, she quietly leaves immediately her shift is over, and arrives home at five thirty. The twins are very pleased to see her, and demonstrate their delight by smothering her in sticky kisses, which is normal, expected and sweet, and then turning into various forms of feline and licking her. Ugh. And it scrapes, feline tongues being somewhat more rasping than soft. She responds by hugging them and then petting till they stop licking and snuggle into her lap. It appears that she has one cub and one kitten, which is definitely a lapful of snugglement. Since they can't see her, she looks lovingly at them both, and then applies a loving look to Castle too, who's had to put up with the terrors all day. He seems pretty happy, so nothing too dreadful can have happened. Or he actively participated in said dreadfulness, which is equally likely.

"Grandma is coming, and Alexis," Castle tells the twins, as they wriggle and squabble around the floor and Beckett's lap.

Petra switches back, very smoothly. Beckett is instantly worried.

"Has she been practising all day?"

"Yep. She's getting very good at it."

"Can we teach her only to change when we say change?"

"Right now we can't even manage potty training, so how do you think that'll go?"

This is true. At just two, the twins aren't quite ready yet. There are two small potties in the upstairs bathroom, in hope. They are perfectly clean. Mostly, they are used by the twins for whacking each other when one or other parent isn't quick enough to stop it, or as hats, or collection points for small toys before they are poured out on the floor where they can be stepped on.

"Badly," Beckett says gloomily. Castle comes to sit next to her. The twins bounce into their laps, and out again, in pursuit of each other and their toys. For once, they have stopped fighting. David sneezes, and follows Petra into toddler-ness. Castle grabs him, and wipes his nose. He objects. Petra smirks, and changes without sneezing. David emits a toddler growl of disgust.

"No 'tishoo," Petra says very smugly. David growls again and pouts. Beckett picks him up and kisses the top of his head. Castle pouts, hopefully.

"Later," Beckett murmurs. "I don't think the twins need to see that sort of kiss. I don't think your _family_ need to see that sort of kiss."

He stops pouting. "When can we get O'Leary round again? Isn't it time I chased you up and down Central Park?"

"Let's get through this first. Anyway, we'll go up to the cabin. Plenty of room for panthers there."

The door sounds. Beckett gathers up the toddlers and takes them upstairs. No point spoiling the surprise, now, is there? Besides which, they want to explain to both Martha and Alexis at once, rather than twice, with added hysteria the second time. She supplies the twins with sippy cups and enough stuffed toys to open a shop, and slips out while they're fully occupied squabbling over the correct distribution of two identical teddy bears. Petra wants both bears. David wants fair shares. Beckett wants a shut door and no noise to which she needs to pay attention, and has therefore ensured that there are no toys which can cause blood or bruises.

Downstairs, it transpires that Martha has arrived first, which is helpful, because she is distractible with a glass of wine and an open ear to listen to her latest thespian triumphs. Alexis arrives five minutes later, just in time. The twins' tolerance for being left alone is no more than fifteen minutes.

"So what's the occasion, darlings?" Martha asks. "Have you an" – she wiggles her eyebrows – "interesting announcement for us?"

"Grams!" Alexis squeaks, blushing. Even after graduating, she obviously still doesn't like considering that her father might be having sex.

"Yes," Castle says, "but not the one which your salacious expression clearly expects."

"Oh?" Martha emits in her best Grande Dame tones. "Well, out with it. I'm quite fascinated."

Castle exchanges a glance with Beckett which conveys _you sure will be. Or you'll faint_.

"Before we tell you, you _both_ have to understand that this stays strictly within the family. You can't talk to anyone about it." Martha looks mutinous. "No-one. If you can't do that, then leave." Castle's tone leaves no room for doubt or disagreement.

"Really, darlings, I'm sure this is totally unnecessary. Nothing is that bad."

Alexis is regarding them with a piercing stare. She, at least, has picked up on the importance of the statement.

"Grams, whatever it is, it's important. So sign up, or go home."

"Of course I'll keep it a secret, but I think this is ridiculous. Who'd care for more than a minute anyway?"

Castle raises his eyes to heaven. Beckett steps in.

"The twins have a – hm – genetic issue."

"That's awful!" Martha screeches, Alexis in counterpoint at lower volume but no less shock.

"What's wrong with them?" Alexis rushes out. "Where are they?"

"Upstairs, till we explain. They don't need to hear this."

"I should think not!" Martha fires out. "Why, their whole childhood would be shadowed by tragedy when it should be a time of joy and happiness. Those poor, poor children" –

"Mother," Castle cuts through the tragedienne's tirade, "the twins do not have a life-limiting condition."

Not unless they take after their parents' penchant for death-defying situations, Beckett thinks cynically, and hopes that they will pursue boring careers such as accountancy or the actuarial profession. Since having children she has acquired a great deal more sympathy for her father's nervousness about her job than she had previously had.

"Rather the reverse," she murmurs. Castle snorts.

"Thank goodness for that," Martha declaims. "But why the insistence on absolute secrecy? It's not as if you're being pursued by three letter agencies, despite your imaginative theories. If there aren't any problems, then this – even for your over-dramatising tendencies, Richard" – Castle squawks – "is ridiculously cloak-and-dagger. Though on that subject, did I tell you about my next project" –

"Grams, not the point or the time," Alexis interjects, recognising the signs of a monologue. She looks hard at her father. "Dad, just spit it out. What have you gone and done this time?"

"Why does everyone always think it was me?" Castle complains.

"Experience," the three women chorus. He huffs.

"I guess whatever's affecting the twins isn't Dad's fault, though," Alexis says slowly, though Beckett bridles at the use of the word _fault_. If there is _fault_ , which she doesn't admit, it's the squirrel's fault. Or that sonofabitch Sasha. She growls. Castle nudges her and flicks a warning glance. The panther does not need to arrive right now. "Because if it was him, it would affect me too, and he'd have told me about it, or about a risk. So it must be you, Kate." A beady glance is turned on Beckett, who returns it with interest. "I hope it's not serious?"

"It's perfectly controllable," Beckett says, "but you need to be old enough to manage it properly." Castle muffles a very peculiar noise.

"So what _is_ it," Martha asks impatiently. "I want to see my darling" – both Castle and Beckett choke – "grandchildren. Do hurry up."

Castle looks hopefully at Beckett. No way. His family, his turn to explain. She had to deal with Gates. She glares back.

"Um, Mother, Alexis, um… you know my cat Onyx?"

"Yes? Has it infected the twins? I told you you should rehome it."

"No. Um… well… she's Beckett," Castle blurts.

"Ha-ha," Martha says. "Very good, Richard. Did you get us here just to prank us?" She turns to Beckett. "Did you know he was going to try that? Really, Katherine, I thought that marrying you would make Richard more sensible, not less."

"No, _really_ ," Castle says. "Beckett is Onyx."

"Dad, I don't want to know about your private predilections. Keep them to yourself, _please_."

" _Listen_ ," Castle says forcefully. "Beckett is a shapeshifter. Specifically, a cat."

Both redheads stare at him. Martha downs the remains of her wine and refills her glass.

"Clearly you have had too much wine. Your poor children. And poor Katherine, too," she says regally. "It must be so difficult, dealing with my son's delusions."

"Beckett," Castle says plaintively.

"Why me?"

"You're prettier." He widens his pathetically pleading blue eyes.

"Oh, _okay_. But _you_ get to go recover the twins."

Martha and Alexis regard them as if they are insane – and then Onyx appears in Beckett's place.

Martha downs the refilled wine in one go. Alexis yelps. Beckett reappears.

" _Now_ do you believe me?" Castle says, arriving at the bottom of the stairs with both twins.

"Mama was a cat!" Petra says happily. "I a cat too!"

"Me too!" David yells. "Looka me!"

Both of them change into kittens: Petra quietly, David with a sneeze.

Martha downs another glass of wine. Alexis yelps more loudly. Castle puts down both kittens, who scamper to their mother and then, having stayed by her only for a half-second of petting, scramble for their grandmother and big sister.

Petra changes back, purely to be able to talk. "I a cat, Gramma! Look! An' I a bigger cat, too."

"A bigger cat?" Martha says, faintly, searching for some last drops of wine in the empty bottle.

"Ah," Castle says. "We…er…"

"There's _more_?" Alexis screeches. Both children wince. David mews unhappily.

"I'side voice," Petra says annoyingly.

"Shush," Beckett says. "That was rude."

"So'y."

"If you have all quite finished?" Castle says. Beckett kicks him warningly. "Um… yes. Beckett is also a panther."

Both twins decide to turn into cubs, to prove the point. Beckett wonders irritably if they understand a _lot_ more than she thinks they do. That change was extremely unhelpfully appositely timed on Castle's words.

"You call this a genetic issue?" Alexis forces out. "It's not _possible_. That's not genetics. It's not _logical_." And then she makes the next step. "Even if it was logical the gene should be recessive" – there is a horrible pause – "Dad, are you one too?"

Castle nods.

"Why didn't you tell me? Why am I not one? You've lied to me all my life" –

"No, I haven't, because I wasn't one for most of your life."

Alexis turns on Beckett. "What have you done to my dad!"

"Nothing he didn't want and ask for," Beckett replies coolly.

In the background, Martha is sitting on the floor holding her wine glass in one hand and petting the cubs in turn with the other. They're both looking at her worshipfully. She empties her glass, hiccoughs delicately, puts the glass well out of the way and devotes her entire attention to her adorable grandchildren, completely unfazed by their shifting forms. Unlike their grandfather, Martha appears to be delighted by two toddlers bouncing all over her and the sloppy kisses she receives.

* * *

 _Thank you to all readers and reviewers._


	3. Chapter 3

**Chapter 3**

Alexis is entirely unimpressed by the situation. This is quite confusing. Beckett would have expected Martha to have histrionics and Alexis to be fascinated by the scientific improbabilities. Instead Alexis is freaking out and Martha taking it all in her stride.

"What do you mean _nothing he didn't want_? How can he have wanted to be a cat? My dad isn't a cat!"

"She sounds just like your dad," Castle says to Beckett, unhelpfully.

"Your dad found out and then whined until he got to be one too," Beckett says to Alexis, who makes a disgusted face.

Castle huffs.

"This is so _not cool_ ," Alexis squawks. "I'll be a laughingstock."

"You agreed not to tell anyone," Beckett points out. "And just so you know, Captain Gates will treat any such report as resulting from drink or drugs."

"If you want to see your siblings in an experimental lab, along with Beckett and me, that's your choice," Castle says quietly.

"Don't be ridiculous, Dad. But how can you have wanted to be a cat?"

"Because it's totally cool." Alexis glares viciously. "Mostly, I'm a panther. It's Beckett who likes being a cat."

Alexis yelps again. "I can't believe I'm even having this conversation." She notices Martha's position. "Grams, aren't you" –

"Why should I be, darling? Your father has done so many insane things in his life, shapeshifting is relatively mild. And my grandchildren are quite adorable in any form."

In the background both have turned to panthers and are play fighting – though there is rather less play than fighting. Adorable seems something of a stretch.

"Just look at them, sweetie. They're so cute."

Petra tries to bite David, and receives a claws-out swipe in return. _Cute_? Beckett thinks. Surely Martha hasn't had that much wine yet?

"But Dad's a _cat_."

"Panther," Castle insists.

"If it makes him happy, then I'm happy. It's not like he's running round Manhattan eating people, is it?"

Beckett and Castle both look slightly conscious. They don't eat people (squirrels, now…) but a number of criminals have been scared within an inch of their lives: frequently corresponding with stressful moments in the Beckett-Castle household – or irritation with Captain Gates, or Ryan, or Esposito – or anyone, really. Chasing criminals in panther form is really an excellent tool for relieving stress. Almost like meditation, in fact.

"I guess," Alexis says doubtfully.

"I'm sure. Now come and play with your siblings." Martha's tone brooks no resistance. Alexis reluctantly moves to settle down beside her. The twin cubs bounce into her lap. Without conscious volition, her hands pet them. The twins, whether kittens or cubs, are very pettable: two hyper-bouncy balls of silky fluff.

"See, sweetie? Perfectly wonderful. Now you play with them for a little while. That's what big sisters are for."

Martha rises elegantly from the floor and re-seats herself close to Castle.

"So, kiddo, another fine mess you've got us all into."

"It wasn't me!" Castle squawks. "Why is it always my fault?"

"I was a cat long before I met any of you," Beckett says wearily. She is already so over this explaining business.

"Oh?" Martha says inquisitively. "That sounds like a _fascinating_ story."

"Not really," Beckett says repressively.

"Maybe another time." _Maybe never_. "So Onyx was actually you?" Martha beams, brightly beady-eyed. "Well, well. That certainly explains a lot. A bit sneaky, but all's fair in love and war."

Beckett represses a blush. That particular phrase carries some very – er – _interesting_ memories. Not to say salacious. She can feel Castle smirking. Sadly, kicking him would invite even more intrusive questioning.

"Anyway" – Martha leans forward confidentially – "I've always wanted to see a big cat up close. Would one of you change for me?"

Beckett's jaw drops open. This one is _definitely_ for Castle. She is not letting Martha pet her. Oh, no. The only person who pets her panther is Castle. The only person who pets her _cat_ is Castle. She forcibly stops herself thinking the next sentence. Further synonyms for _cat_ are not required. She fixes Castle with a hard stare. He shrugs, and stands up.

"Oh, _my_ ," Martha says. Castle-panther preens. Beckett notices that he is also a significant inch or two out of range of her hands. "It" –

"He" –

"He's so much bigger than they look in zoos."

"Yes."

Castle sits and smirks smugly, even as a panther.

"Well, I never expected my son to be a feline, but he's very impressive."

"That's _Dad_?" Alexis squeaks.

"Dada play!" David shrieks happily, sneezes, becomes a cub and bounces over to his father, play-batting at him. Martha sighs sappily. Alexis squeaks again. Castle amiably bats back at his son, very carefully, and suffers his paws to be trodden on, his tail to be chased and his stomach to be bounced over.

"Mama play too!" Petra demands.

"Not now, sweetheart. Mommy's talking to Grandma and Alexis."

"'Lexis play." Petra tugs at her. "'Lexis be cat with me."

"She can't be a cat. Why don't you stay a girl?"

"No! Wan' 'Lexis to be cat!" Petra shouts.

"Inside voice, please. And Alexis can't be a cat, so you need to stay a girl if you want her to play."

"Don' wanna. I _cat_. 'Lexis cat."

"I'm not a cat," Alexis says, picking up the hint.

Petra's face turns red and scrunches up. "Wan' _cat_!" she wails. Fat tears trace down her face.

Beckett recognises impending and loud disaster and sweeps her up. "No cats," she says soothingly. "Look. Grandma, Mommy, Alexis and you aren't cats right now." Petra whimpers, not convinced. Beckett looks at her watch round Petra's miserable form, and knows that it's a result of tiredness. "Time for your bedtime milk," she says, and settles her against her shoulder as she stands up, patting her back. "Let's go get it."

Usually, that works just fine. Unfortunately David is still playing with his father, and Petra spots it. She emits an ear-shredding wail. " _Dada_ cat! Me too! No mi'k! _Play_!"

"Nope," Beckett says calmly. "You have your milk with me."

Petra, still trailing a string of complaints at full volume, is removed to the kitchen and supplied with a cup of milk. Beckett retains a hand around it in case she tries to throw it. It wouldn't be unheard of. Astonishingly, Petra hasn't tried to change. Beckett attributes this to a combination of temper and exhaustion, and – since Petra is in her lap and a panther cub having a tantrum is detrimental to both clothes and skin – is thankful.

Castle spots the application of milk to Petra and changes back to himself, picking up David, whose small furry legs wave fruitlessly from his hand. Martha smiles adoringly. "C'mon. Milk time." David recognises the word, sneezes, and is a toddler, who is shortly tucked into Castle's broad shoulder and then convinced also to drink his bedtime milk. Despite severe provocation on many occasions, neither cup is laced with a sedative.

"Bedtime."

"NO!" the twins screech in unison. Their refusal makes no difference at all. Beckett is quietly implacable about the need for bedtime. She carries Petra up, Castle brings David, and washing, teeth brushing and sleepsuits are achieved with only a small amount of wailing and complaint. It is, they have rapidly found, perfectly possible to brush panther or kitten teeth. This doesn't stop either twin trying it in the hope that _this_ time, unlike the previous two times, it will work. One of the key disadvantages of non-synced shapeshifting is that the twins' options for attempting delay and distraction have multiplied, and they are testing them at every turn.

The children are tucked into their cot – they still share it: they'd tried two cots in the same room, right next to each other, but it had been completely ineffective except for the production of large quantities of unhappy screaming. Since sleep is a necessity for all of them, a larger cot had been purchased. Silence – and sleep – had thereby been achieved. Beckett looks at it, and detects scratches.

"We need to get them their own post," she says to Castle, as she picks up tonight's story book. It's _her_ turn. Castle's a better natural reader, but she's not letting him have all the fun. Today, it's a silly little duck called Zachary Quack. The fact that it being her turn to read the bedtime story will leave Castle to face his family without her for a few moments has nothing to do with her happiness. That's purely because her tiny terrorists are clean, sleepy and genuinely adorable, of course. Castle kisses them, Beckett opens the book, and soon there is peace. She gently kisses each little head: dark for Petra, lighter for David, and slips out, closing the door so that any nocturnal wanderings are limited. She has no desire to be trying to find small animals in the small hours, and she certainly doesn't want them to burst in on any adult time with Castle. They'll need enough therapy when they realise there's no-one else like them: they don't need any other issues.

"All tucked up?" Martha asks maternally.

"Yes. More wine?"

"Yes," Alexis says fervently. "Please." Castle looks at his daughter. "I'm over twenty-one, Dad. And right now, I need a drink."

Castle stares at his daughter's wide, scared eyes and tight face, and pours. Alexis throws it back in a manner very reminiscent of her Grams and holds the glass out again. Beckett ignores Castle's horrified glance and pours. Women should stick together in the face of horrible shocks, and she hasn't forgotten her original reaction to becoming a cat. The caterwauling had been particularly embarrassing.

"Look," she says, "I know this is a bit of a surprise" –

"A _bit_?" Alexis squawks.

"Shhh," Castle says. "You'll wake the twins, and trust me, you really don't want that."

"Not the time, Castle – a bit of a surprise, but honestly, it's still just us. We just got landed with a bit of – er – additional genetics along the way."

" _You_ might have, but Dad _chose_ it."

"Yes, I did. It's so _cool_ , pumpkin."

"That's just typical of you," Alexis argues. "Just because something's cool doesn't mean you have to do it."

"But if I hadn't, Beckett would still be all on her own. People shouldn't be lonely."

"You mean there aren't any others?"

"Nope," Beckett says. "Just us four."

"Used to be just you one."

"What sort of grammar is that for a writer?"

Castle pouts. "Mine," he says sulkily.

Alexis looks resigned. "Always trying to make the world a better place. I guess I should have known. And I _really, really_ don't want to know how you got turned into a cat. Ever."

"Probably wise," Beckett says dryly.

"But they're totally cute."

"Right now," Beckett says dryly, again, thinking _that's because they're asleep_.

"Can I have another drink now?"

"Sure," Beckett says, and pours some more.

Alexis and Martha stagger out, leaning on each other, some time later.

"That went okay," Beckett notes.

"More or less. I thought Alexis would be really keen on it. She's my daughter."

"She's your _sensible_ daughter. We've just upended her world."

"But my mother…"

"Your mother is an actor. She's used to believing six impossible things before breakfast."

"She hasn't played Alice. The Red Queen, now..."

"Anyway. Two down, one to go." She listens carefully to the monitor. The twins are well past the stage where – normally – a monitor would be required. However, two mischievous kittens or cubs can create havoc with the minimum of noise, and therefore the monitor had swiftly been reinstated a mere two days ago. However, there are no worrying sounds from above, therefore it will be safe to snuggle into Castle and possibly provide that kiss that he didn't get earlier.

A kiss is duly provided. The first brief peck is a mere tease, just to make sure Castle is paying attention. He is. An instant later he's swept her into his lap and is delivering a kiss of his own which is anything but a peck, or, for that matter, anything but brief. She slips her hands round his neck – just in case he tries to escape, which has never happened and so proves the efficacy of the method – and kisses him enthusiastically in return.

A little while later they repair to the bedroom, shortly before a trail of clothes decorates the floor. (Pre-children, the clothes would have decorated the family room, and been cleared up in the morning. That's all past.) Some time after that they are happily entwined, lax and satisfied.

"What do you think'll happen tomorrow?" Castle asks sleepily.

"Lanie will screech, Espo will use some words I don't want the twins to learn, and Ryan will faint," Beckett replies cynically.

"'Bout what I thought." He relapses into unusual silence. "Do we still think it's a good plan?" he asks.

"It was never a good plan," Beckett points out. "It's just that all the other plans are much worse, and doing nothing was even worse than that." She smiles softly at him. "I'll put my leave request in and we can go up to the cabin for a week. Teach the terrible twins a bit about Nature." The smile turns evil. "There are deer up there…" she entices.

"It's not hunting season."

"Panthers don't have a hunting season. We just hunt. C'mon. A nice long chase through the woods…"

"I'll catch you," Castle says lazily.

"I'll _let_ you catch me, if you promise to be good."

"Oh, I'll be good. I'll be really, really good… at being bad." He rolls over, and pins her down, and shortly proves just how good he is at being bad.

* * *

Over breakfast, which is a moderately messy affair involving lessons on the correct use of a spoon – the four hundredth repetition this week of "In your mouth not in your hair" carries more irritation than child-centred tuition – and the choking down of the adults' meal while trying to prevent Food World War III, no better ideas have come to mind. Possibly this is because the minds in question are also trying to deal with the problem that high chairs were designed for human children, not for kittens. Or cubs.

In short, the twins have discovered that it is far easier to eat as cats than to try for the fine motor control involved in inserting a spoon correctly in one's mouth.

"Any good ideas, Castle?" Beckett says desperately, watching the two cubs hoover up their breakfast. "They have to learn to eat as humans, and if they just change every time it's going to be dreadful."

"Um… we could put them down, and leave the food up, and tell them that food is eaten when they're boy and girl, not cats."

"That might work. We might need to refine it a bit when we go upstate, but let's try. I'll take David" –

"Why do I always get Petra?"

"Because you manage not to be clawed or bitten."

Castle grins. "Must be all the practice from dealing with Onyx," he says, and ducks out of the way of her playful swipe at his ass. "See?"

In a smoothly co-ordinated start to the manoeuvre, they each pounce upon one cub and remove their victim from the high chairs. Beckett takes David well away from the table.

"You have to be a boy at the table," she says, "like Daddy."

David sneezes, and becomes a boy. "Why?" he asks, peeking cutely at her.

"Because that's how we eat."

"Why?"

"So you can eat at Grandma's."

"Yes," David says happily. Beckett rejoices. "Gramma's now!" She laments.

"Not now. Breakfast time now. Stay a boy, please." She puts him back in his high chair and hands him the spoon.

"Not like 'poon," he pouts. He resembles his father to a quite extraordinary degree. Beckett treats his pout rather differently, however. She plops a kiss on his chubby cheek.

"Big boys have spoons," she says enticingly. "Like Daddy." David always wants to be like Daddy. This may prove to be very worrying very shortly.

"Dada have 'poon?"

"Yep. Daddy has a spoon." She'll fret about the technicality of knives and forks later. Along with the proper timing for the uses of claws and sharp teeth.

"Where my 'poon?"

"Right here."

David grabs the spoon. Beckett is so relieved that he's listened to reason (his father never does) that she doesn't tell him off for snatching. He digs into his breakfast, and discovers, as have so many small children before him, that spoons carry more food than can neatly fit into one's mouth. A substantial quantity of porridge rapidly decorates his happy face. Beckett counts this as a win.

Across the room, Petra is not proving nearly as compliant. She is still a cub, for a start. Castle is regarding her firmly.

"You have to be a girl to eat your breakfast," he says calmly. Petra glares at him. "No glaring." She growls. "Growling doesn't work on me. Now, be a girl and have breakfast or stay a panther and don't." Petra turns her furry back on her father. He puts her down and comes back to finish his breakfast, ignoring her sulks.

"Petra a cat," David says. "Naughty Petra. No eat."

Sadly, Petra hears this. She turns back to human. "Nasty!" she yells, and aims for David's high chair. Before she can attack it, she's caught. This is not popular. Beckett removes her tantrumming daughter to a safe place, being upstairs, regrets that she hadn't eaten her own breakfast even faster and regrets more that she hadn't waited for Castle to stop Petra, and plonks her in the cot.

"Time out," she says briskly. "You're to be a girl at table, like Mommy. And no pushing David's high chair over."

"He _nasty_ ," Petra shouts.

"Not relevant. If you had turned into a girl when Daddy asked you, you would be eating your breakfast."

"Don't want it."

"Okay," Beckett says calmly. "Time out." She shuts the door behind her and returns to her own neglected breakfast. Downing her coffee, she wishes it were whiskey. Petra is a tough gig. Castle has clearly administered admonitions to David, who is looking subdued.

Two minutes pass, in which both adults have finished their breakfasts. There is a worrying silence from upstairs. David has bedecked himself with porridge and will need washed before anything else happens.

"Toss a coin for it?" Castle says.

"Nope. You get to wash David. I haven't time to change and wash him, and he likes to splash. I'll take Petra." Take her to the zoo, possibly, and leave her for a few hours. In the panther enclosure. Though by the time Beckett retrieved her she'd probably be running that show too. Petra is very disturbingly strong-willed, and very unwilling to give up whatever idea she might have in her toddler head no matter how good the arguments against the action. Beckett is not reassured by this resemblance to herself. It's a _good_ trait – in an adult. It is _not_ a good trait in a toddler.

Petra has occupied her two minutes of time out in throwing their large quantities of soft toys all around the room, and is sitting in the middle of them in the form of a very sulky kitten.

"Mommy's going to work," Beckett said. "Come downstairs to say bye-bye."

Petra converts herself back to human. "No work."

This is a common complaint. "Yes, work." Beckett thinks of a distraction. "Uncle Espo and Uncle Ryan are coming tonight. And Auntie Lanie."

Petra is instantly distracted. Her sulks become a broad smile as she stretches her arms out to be picked up. Beckett obliges. "What do you say?"

"So'y, Mama."

"C'mon then. Downstairs." Petra latches on with her usual strangling grip and soggy nuzzling.

Downstairs, Beckett waves everyone goodbye with the usual round of kisses and a swift exit before anything _more_ can go wrong.

Catching killers is _so_ much easier than toddler wrangling.

* * *

 _Thank you to all readers and reviewers. Sorry about Thursday. Work went mayhemic._

 _To all who celebrate Thanksgiving, I hope you had a very happy holiday._


	4. Chapter 4

**Chapter 4**

Beckett reminds Ryan, Esposito and Lanie that they are invited round tonight, receives enthusiastic acceptances and requests for pizza and beer, further reminds them all that there are to be no presents bought or brought since she could restock Macys as it is, and departs to arrange for pizza and beer.

Home is surprisingly placid. Both children are sitting eating their dinners – as human, which is amazing, and with spoons, which is astounding. Castle may well have hypnotised them, Beckett thinks. Maybe he can show her how he did it.

"What did you do?" she admires.

"Took the food away every time they weren't human. Gave it back when they were." He looks round. "And again." Plastic plates are removed as the toddler twins are now kittens.

"Children get dinner. Cats don't," Castle points out in long-suffering tones.

They change back, and exhibit identical pouts. "Dada naughty." Petra says.

" _My_ dinner," they both complain, as the plates stay away.

"Daddy is _not_ naughty," Beckett says, which is only true for a given value of naughty which could be explained to children. Castle is frequently very naughty indeed, in a very adult fashion. "Only children get dinner."

The plates are returned.

"And now you're children, you get your dinner."

Beckett thinks about recording that phrase. She can see the future, and it involves a lot of repetition.

"The gang want pizza and beer. Do I need to order?"

"Already done, while the terrorists had a nap."

Beckett produces a beautiful smile. Castle, despite all attempts to obscure it, claiming that he has a reputation to uphold, is highly efficient. She'd _rather_ he was out on cases with her, but they've managed that by her bringing it home so that he can play too. Strangely, Gates has never been informed about this workaround, though Beckett is pretty sure that she's guessed given some of her barbed commentary.

"Thanks, babe," she smiles. Further commentary is prevented as it becomes obvious that dinner has been finished. Beckett removes Petra first, takes her upstairs where she can be bathed – there are tomato fragments in her hair and her face is as good as a menu – and starts to run a bath.

"You're all over tomato," Beckett points out. "It's supposed to go in your mouth, not in your hair."

"Bath!" Petra says, ignoring the instructional point with aplomb.

"Yes, bath. Wash you all clean."

"Wan' bath. Wan' duck."

Beckett certainly will want to duck. The twins are splashy. However, Petra probably means that she wants to play with the rubber ducks. Castle brings David upstairs, equally covered in dinner. Shortly, both of them are noisily splashing in the bath and zooming the ducks at each other. This is just fine. Happy twins are a delight.

Naturally, it doesn't last. Petra decides that this evening is a good time to discover whether kittens like water, finds that kitten-she doesn't, tries the panther-cub, finds that she doesn't like water in that form either, turns back to human and wails loudly.

"Nasty bath," she howls. "No bath." She tries to clamber out. Beckett plops her back in and rapidly washes her.

"Baths are fun for children. Not cats. Be a girl in the bath and a cat when you're dry. Children play with ducks. Cats don't."

"No' fair! Nasty bath!"

"Out you come," Beckett says, since Petra is all washed. She wraps her daughter in a large, cosy towel and lets Castle catch the small would-be Houdini while she washes David into relative acceptability and then dries him with enough tickling and play to make him happy. She does accompany it with a naughty glance at Castle, indicating the possibility of play for the two of them later.

Both toddlers in their sleepsuits, clean and adorable; they all go back downstairs until the doting brevet-relatives arrive. Castle and Beckett disport themselves on a cushion sized for two adults on the floor, and the twins involve themselves in block building, instrument bashing (Castle swears they will be talented musicians. Beckett has ordered earplugs) and a significant amount of changing form and bouncing into parental laps where petting is sure to be available.

"How d'you want to play this?"

"Well, last night we kept them out the way for the first few minutes…"

"Yeah, but… I think we should just let everyone catch on."

Beckett grins nastily. "That's unkind."

"But fun." Castle looks at the squabbling kittens. "How many comments have you heard about how easy being a stay-at-home parent is?"

"Too many," Beckett agrees. It's going to be good for the gang to realise the unusual challenges with which they are dealing. "Okay, let's just keep them downstairs. Everyone should be here soon."

Not long after, the door sounds. At this point, the toddlers are terrorising a cushion and are human. It's entirely accidental, Beckett knows, since the twins generally seem to do whatever will make their parents least comfortable, but it's helpful.

Castle lets all three visitors enter. Lanie dives straight for the toddlers. Her insane love for babies and small children is undiminished. Beckett is still wondering if it's possible to have her committed. Of course Beckett's toddlers are adorable (in small doses, and usually when asleep) but everybody else's small children are revolting and should be kept far, far away, possibly by drawing a gun.

Ryan wanders over to greet the twins, who are bouncily delighted to see him. David is especially delighted. Ryan is always happy to play with him, and usually Castle joins in. The three boys are quite happy to be boisterous together, though Ryan stops it going too far.

Lanie is playing happily with Petra, who is behaving far more nicely than she ever usually does. This might be because Lanie's kickass attitude is keeping her in line, but more likely it's because Lanie has been known to bribe her with chocolate chips and Petra is exceedingly good at remembering her own best interests.

Esposito is not a child friendly person. This goes along with his general demeanour. Esposito is not a people person and doesn't care who knows it. He sits at a very safe distance from the tiny terrors and shrinks back every time one looks as if they might come within ten feet. As a consequence he is the only person currently drinking beer.

He is also the only person who pays any real attention to what the toddlers are happily squeaking, only because his cop instincts are so ingrained that he believes everything to be a _clue_. Beckett is busy shoving vast quantities of pizza in the oven – but if she follows her usual practice, not switching it on till the twins are in bed - and everyone else is playing with her toddlers. So Espo is happy simply to keep out of the way and listen.

"'Anie, I a cat!" Petra is cheeping. "Big cat. Little cat."

"Sure you are, honey. You're a really cute cat."

"Mama a cat too."

"Sure she is."

"An' Dada."

"You've just got the cutest imagination, sweetie."

"B'ack cats."

Esposito controls his urge to vomit at Lanie's sugary tones. In self-defence, he listens to the male side of the party.

"Dada play," David chirps. He peeps at Ryan. "Ry play too."

"Sure, kid. Baseball?"

"Silly Ry. Play with tail."

Ryan goes bright scarlet. "Play with my tail?" he says in a high-pitched squeak.

"Like Dada."

Esposito is absolutely horrified. Play with tails? Surely that's illegal? "Beckett?" he calls.

"Yeah? What is it?" She pads over.

"David," Castle says, "Uncle Ryan doesn't have a tail." David stares at his father.

"No tail?"

"Nope."

The small face crumples. He clambers up into Ryan's lap and pats his cheek. "Poor Ry. No tail."

Esposito tries futilely not to snigger. Then he notices that Beckett is tensely expectant.

"I got a tail," David cheeps. "Look!"

Ryan screams and throws David at Castle, who catches him very neatly and smooths his fur.

"Madre de Dios!" Esposito yells. "What the actual f" – Beckett elbows him before he says the word. Lanie looks around.

"Me too!" Petra shrieks, and changes. Lanie shrieks even louder than Petra. "What the _hell_ , girl?" Petra bounces into her lap. Lanie shrieks again.

Esposito has his hand on his gun and is swearing continuously under his breath as he takes in the chaotic situation in front of him. Ryan is scooting as far away from Castle and David as possible while apparently praying to all the Catholic saints, and Lanie is still shrieking none too quietly as Petra tries to clamber up her front and lick her face. Since Petra has attached her claws to Lanie's rather pretty top, Lanie can't simply fling her away without displaying much more of her anatomy than she'd like.

Castle and Beckett exchange extremely nastily satisfied glances.

"Now, which one of you was it said that Castle had it easy being at home with the twins all day?" Beckett asks in a delicately interested tone with considerable malice underlying it. "Espo, I think that one was you. And Ryan, you suggested that he'd got – what was it? Oh yes – soft and lazy." She skewers them both. "Wanna change your view?"

While the boys are gibbering, Beckett crosses to Lanie and very carefully detaches Petra, without damage to her top. Lanie doesn't look as pleased as she could do about that. Beckett fusses over Petra, who is sporting a smugly feline expression which she really shouldn't develop till around age fifteen.

"No claws," Beckett says warningly to Petra, who mews, not complaisantly. "No. Claws means time-out."

"What the freakin' h" – Beckett nudges Lanie, hard – " _heavens_ is that?"

"That's Petra. _My_ baby."

Lanie gibbers. Frequent references to deities and saints are heard. Beckett thinks snidely that she's never seen so many people get religion so quickly outside of a revival meeting.

"This ain't possible," Espo declares, in defiance of all the facts. "I ain't here. I'm asleep an' dreamin'."

"It's real," Beckett says forcefully. "These are our twins." She moves to sit down beside Castle, each with a cub on their laps. Ryan whimpers and scoots even further away. "Shall we?" she says to Castle, with a bright, dangerous smile.

"Why not?" he shrugs. "One, two, three" –

All three human adults scream as there are suddenly _four_ black panthers in the room, the larger pair of which are smiling. Or something. There are substantial quantities of sharp white teeth on display.

"Nooooooo!" Ryan wails. The biggest panther is between him and the front door, which he had been eyeing up.

Beckett-panther puts her paws over Petra-cub's ears – Castle does the same for David-cub – as Esposito lets loose a long string of profanity including a number of words which Beckett has never heard, all without pausing for breath. Lanie produces a similar stream in disharmonious counterpoint. Ryan simply continues to whimper.

Beckett changes back. "Have you finished?" her cold tones cut through the din. Gradually, the noise reduces to the occasional gasp and whimper.

"This ain't _real_ ," Espo pleads. "You ain't the guys we know." He shifts in his seat, away from all of them.

"Do I have to bite you on your dumb ass to prove it is?" Beckett enquires acidly. "It is real. This is us. Can you stop looking at us like we've come out a bad horror movie?"

"But it can't be," Lanie squeaks. "It's not possible. You don't exist!" She's shuffled several feet towards the exit.

"I'm sitting right here. How can you say we don't exist? I've been working with you all for years and now you find out I'm a little different from what you thought I was suddenly I've got the plague? You're all edging for the door."

"But… but… but you're not _human_!" Esposito blurts out, which doesn't help anything at all. Castle-panther growls fearsomely.

"And this makes a difference how? Try saying that sentence with _you're not white_ and see how you feel."

Beckett's temper is poised on a knife-edge. She hadn't expected her _friends_ to react this badly. The two cubs are now growling too. Castle is flexing his claws in and out, and Ryan can't take his eyes off them for a second. True, they are long, and sharp, and deadly. She strokes his back, which is at least as much to soothe him as her. Castle doesn't often lose his temper, but when he does the fall-out is spectacular. They don't need that right now. She gathers the cubs into her lap and pets them too.

Petra changes back to a toddler, looking utterly miserable. "No play?" she whimpers. "Mama cross?"

"Mommy's not cross with you, sweetheart." Beckett cuddles her.

"They cross," Petra says, which is possibly true, although terrified might be a better word. Beckett doesn't answer that immediately.

"They're a bit surprised," she eventually temporises.

David wriggles in her lap, and then spots Castle's tensely twitching, almost lashing tail. Tail-chasing is David's favourite occupation, and if no other tail is available he will occasionally chase his own, which results in dizziness and crashing into things. Right now, however, Castle's tail is moving restlessly, and David is very, very tempted. He's watching it intently. When it next comes near, he pounces.

He misses, and scampers after it. Castle-panther relaxes almost instantly, focuses on his son, and keeps his tail moving just out of reach.

Ryan laughs, suddenly. Everyone looks at him. "Now I get it," he says. "He just wanted to play chase." He grins. "I was really worried about what you were doing." He gazes at David-cub, who is batting at his massive father and clearly looking for some roughhousing, panther-style. Castle lazily bats back, very gently, which still slides David over the floor. He meeps happily and bounces back for another go. David is easily kept happy.

"Okay, Beckett. Spill. Why'd you never tell us?" Beckett stares incredulously at him. Ryan flushes. "Oh. Well. Okay. Um…yeah." Esposito and Lanie are still speechless. "But _how long_? Always? And what about Castle? I mean… surely someone would have noticed when he was tomcatting about town before he met us" – he realises what he's just said. "Didn't mean that pun," he squirms. "Anyway. How long?"

Beckett fusses over Petra for a moment, till her unhelpful daughter wriggles to be put down and deprives her of any protection. Once put down, Petra toddles round to her father, pushes David out of the way, which raises an indignant miaow, and attempts to climb up him, aiming for his whiskers. Castle emits a warning growl, which merely causes Petra to aim for his ears while David essays a further assault on his tail while Castle isn't looking. The pincer movement works. Castle yips as David takes a firm grip on his tail with his sharp little teeth, and yips again as Petra reaches a black ear. He shakes David off, which results in happy squeaks, and changes back to human.

"Leave my ears alone," he says to Petra. "Mommy does enough damage." Beckett casts him a dyspeptic glare. He removes Petra's fingers, and cuddles her. David comes in search of cuddles too.

"Wanna play," Petra says. "'Anie won't play. Don't like 'Anie."

"That's not nice."

"Don't care. 'Anie not nice."

 _Out of the mouths of babes_ , Beckett thinks as she gets a glimpse of Lanie's face on hearing that little gem.

"Since I was nineteen," she says to Ryan, who performs some very obvious calculations. He really must stop counting on his fingers. It's embarrassing when you're north of age ten.

"Before the Academy? How did you get through training?"

"You shouldn't have got through the medical," Lanie says: more accusing than enquiring.

"By _not telling anyone_ ," Beckett states with flat irritation. "Because I knew that I'd get this – nonsense." She manages not to use any words that she wouldn't want the twins to know.

"Okay," Castle says tiredly. He's been remarkably quiet so far, which is entirely unreassuring. The tone of his voice is also not reassuring. Both together indicate that his normal cheerful placidity is seriously ruffled – not to say on the point of snapping. "Can we at least trust you three to keep this quiet? Though if you don't, Gates is already briefed and will shut you down hard if it's mentioned. She was supportive." Beckett blinks at the flat statement. That's a pretty loose use of _supportive_. "Guess we've found out who our friends are. We get that you can't deal with it. You can leave any time you like. Just keep your mouths shut about us. Ryan – that means you don't tell Jenny either."

There is a short, very unpleasant silence. Beckett moves closer to Castle, and collects the children again.

"The door is that way," she says, with a sharp gesture. "It's the twins' bedtime. Goodnight." She stands up with Petra in her arms, Castle follows with David, and all four of them go to the kitchen to organise milk, which is taken upstairs.

The silence that they leave behind is deathly. Lanie, Espo and Ryan look helplessly at each other.

"Panthers?" Ryan says faintly. "That's… weird."

"Never mind panthers, we just got thrown out. Didn't you hear that?" Lanie says. She looks utterly miserable. "My favourite niece doesn't even like me any more."

"Maybe you shouldn't have shrieked and refused to play with her," Espo says snidely.

"You were the one who was racist about them," Lanie snaps back. "And don't think I didn't notice you hiding out on the couch."

"Least I didn't actually throw one of them away like a soda can. And I wasn't racist."

"Speciesist, then. Whatever. You'd've killed anyone who said _but you're not white_ to you."

"Yeah, you didn't push them away 'cause you never got near any of 'em. Beckett's babies an' you won't even give them a hug."

"I don't do kids."

"Reassuring," Lanie says cynically.

"Ugh. That's disgusting." Ryan winces.

"I don't _like_ kids. Loud, snotty and then they cry. Bit like Ryan after the Knicks play."

"Hey!" Ryan squawks. "It's you two who screwed this up. I was getting my head round it when you started making dumb comments."

"Yeah, right. You screwed up just as much."

"I'd've apologised if you two had ever shut up an' let me have a word in edgeways."

"Would you hell. You were screaming like a scared little girl."

"Like you were so cool with it. You were just as scared."

"Are you still here?" Castle enquires coldly, as he and Beckett come back down the stairs.

"You've made it pretty clear you can't cope," Beckett adds. "Take your arguments elsewhere. Our children need their sleep, and your shouting is disturbing all of us."

Castle stalks over to the door, and puts his hand meaningfully on the handle to open it. "Good night," he says. It sounds disturbingly final.

"I'll see you at work, Detectives. ME Parrish," Beckett says. That sounds even worse. She has pulled on her full senior detective persona and rank, which she _never_ does with them.

"But Beckett…"

"But nothing. You can't accept us so you can leave."

"You haven't given us more'n a minute to get used to it. You drop somethin' like this straight in our laps without any warnin' an' expect us to be happy?"

"I expected you to be _our friends_ , not a bunch of bigoted jerks!"

There is another deadly silence.

* * *

 _Thank you to all readers and reviewers. Very much appreciated._


	5. Chapter 5

**Chapter 5**

"I wanna see," Ryan says. "I don't care what the other two think. Sure, I got a helluva scare – an' you two are mean as _shit_ for doing it this way – but I can deal." He turns a cold shoulder to Esposito and Lanie, who are not clinging to each other but look as if they might. "Show me again."

Beckett glances at Castle, who nods. Her turn, she guesses. She shifts. Ryan manfully suppresses his terrified squeal. She yawns, very widely, towards Espo and Lanie, who do not appreciate the display of gleaming teeth, and cringe closer together.

"You're seriously badass." Ryan's voice nearly doesn't quiver. Beckett runs out her claws, admires the way they glint dangerously in the light, and runs them back.

"She is," Castle says, and wanders back to her, sitting down on the floor and unconsciously stroking her fur in a very soothing manner. It stops her wanting to bite. For all she knows right now, it might also be stopping Castle wanting to bite.

Ryan looks at her for a while, evidently thinking. "How come," he says slowly, "if you're both panthers, Castle got that black cat? I mean, how does a panther need a pet cat?"

"Dinner?" Castle flips at him. Beckett growls, and extends claws until they are just touching his skin. Ryan watches her with considerable trepidation. Espo and Lanie cower.

"That's not cool, man. You adored that cat. Where is it?"

"She."

"She, then. Where is it?"

"Um…" Castle says, "um… right here?"

Ryan glurps and goggles. "That cat was Beckett?" he says very faintly. "You dropped freaking _panthers_ on us when she could have been a cute _cat_?" Beckett growls very loudly. She is not cute. She is _elegant_. The twins are cute. Sometimes. Usually when they're asleep and can't wreak havoc.

"What the _hell_ ," Lanie squawks. "You freaked us out when you could have turned into something _safe_?"

"You'd have been just as freaked out," Castle points out. "You weren't complaining about the panthers, you were complaining about us not being human. Which we are. Mostly." There's an edge on that. Clearly Castle's temper is still high.

"That was Espo!" Lanie contradicts, throwing him under the bus without a second's pause.

" _You_ implied Beckett shouldn't have got through the Academy. How's that any better?"

Lanie is silenced.

Ryan is still processing. Unfortunately, Ryan is also still a good detective, and he has an unfairly good memory.

"So Beckett's a cat. Sometimes. And a panther. Sometimes. But when you brought the cat to the precinct you didn't know she was Beckett. Unless you're a seriously good actor, you had no idea. So if you had no idea," he works out, aloud, "then you weren't a shapeshifter then. So how come you…are…now… Oh my God. You didn't." His voice rises to a falsetto squeak.

"Of course he freakin' did," Espo says disgustedly, following the thought. "This is Castle."

"You got Beckett to change you," Ryan concludes. "You're freaking insane."

"This is something I _do not wanna know_ ," Espo states forcefully. Lanie has acquired a very scientifically enquiring impression which is not an improvement on her previous appalled demeanour.

"Good, because we weren't going to tell you." Childish, but understandable.

"This is not scientifically or medically logical," Lanie says crossly. "People do not become panthers. Or cats. Nor do they change other people's genetic make-up so that they become panthers. Or cats. And they certainly don't have children who become panthers or cats. This is _impossible_."

"Stop saying that," Ryan says, just ahead of Castle's looming explosion. "It's real and it's right here. So it is possible." He breathes. "But could you change back, _please_ , Beckett, because those teeth are seriously scary and you keep gnashing them."

He receives a cold green stare, and a baring of said teeth.

"Please?" he says plaintively.

The panther shrugs, and becomes a barely less dangerously irritated Beckett. Ryan just about smothers his sigh of relief, until he realises that the panther could reappear at any moment and if Espo and Lanie don't straighten their heads out pretty quickly it probably will. The atmosphere is not improving in the slightest, though the ire is firmly directed away from Ryan.

"Um…" he says hopelessly. "Um… hold on, you said _Gates_ knows?"

"Yeah."

"Who _else_ knows?"

"My doctor, my dad, Martha and Alexis, and O'Leary. And you three." She glares. "Everyone else has got their heads round it in short order."

"So you've left us till last?" Esposito says combatively, exhibiting all the grace and good manners of a spoilt five year old who is the last to be given a slice of cake at a birthday party.

"Yes," Castle says bluntly.

"If the twins hadn't decided to desync we'd never have told most of you at all."

"Most of us?" Lanie says, seizing on the statement like a starved alligator.

"I had to tell my doctor."

"Why?" Espo says, which wins the prize for dumb question of the decade.

"Babies, dumbass," Ryan scrapes out.

"And O'Leary guessed. But he said he'd always wondered."

"An' Gates is cool with this?" Esposito queries, aggressively disbelieving. "I don't believe that."

"Just as well it's not up to you, then. She is."

"Do we have to carry on with this crap?" Castle enquires with irritation. "Ryan, if you wanna stay for some pizza that's fine. Espo and Lanie, don't bother if you're only going to bitch like you have done. Either get with the program or get out. I don't care which."

 _Well, that's telling them_ , Beckett thinks.

"If we're such good pals why did you never tell me?"

"You really need to ask that after the last hour, Lanie? Listen to yourself. I shouldn't have been able to graduate from the Academy. I'm impossible. My children are impossible. I'm _not human_." She breathes.

"I never told anyone till Castle guessed. If the twins hadn't desynced about three years too early to hide it, I'd never have told anyone else. Because they'll all react like you have. And you're supposed to be my friend. What d'you think the media'll do? Or _researchers_?"

She grinds to a halt, eyes blazing, recovers her temper.

"So like Castle said, get with the program or get out. Just keep your mouths shut."

Behind her back, she crosses her fingers. She'd never expected that her _friends_ would be a bigger problem than _Gates_ , for goodness' sake. Never. And now it's all going horribly wrong because they – well, two of them – can't see past their stupid prejudices. She twines her fingers into Castle's, and curls in, depressed. She wants to be Onyx, who never worries about anything and is pettable; or her panther, whose ferocious attitude is at least more cheerful than she is right now. This is not the happy, fun-filled evening she'd envisaged, where her friends would be first shocked and then take it in their stride and give and take the usual banter. She droops unhappily.

Both of them are staring at her. Castle's fingers are as tense as hers. Ryan is trying to become invisible.

"Girlfriend…" Lanie starts. Beckett is not exuding receptivity. "I'm _sorry_. But this is a hell of a shock, and you never told me in all the years I've known you."

"I said I didn't tell _anyone_."

Matters are interrupted by loud miaowing from the top of the stairs, and some very disturbing scrabbling noises. These are followed by a loud and satisfied mew matched with an equally loud and very dissatisfied caterwaul. There is the clacking of – evidently – claws on the wood of the stairs. Beckett and Castle look at each other, utterly horrified, as – of freaking _course_ – Petra slither-slips down the stairs in panther form.

"Oh, _shoot_ ," Beckett wails, managing to remember not to use any words she doesn't want the twins to learn. "Not _another_ first. How did she escape?"

Petra bounds up to her and promptly changes to toddler.

"You should be asleep," Beckett says sternly.

"Mama play. I cat. Cat not tired. Cat 'turnal _,_ " she emits in a satisfied tone.

 _Oh Christ_ , both parents think, very loudly indeed. And how did she hear _nocturnal_ anyway?

"How did you get out of your room?" Castle asks, rather too interestedly for Beckett's taste.

"Jump," Petra says, which doesn't really explain the mechanics. "Wan' play." She looks around. David is still caterwauling loudly and scrabbling frantically at the stairgate. "Play wif Ry. Ry nice." She glares. "'Anie not nice."

"Don't be rude. Say sorry."

"No!"

"Say sorry or time out." Petra changes to a kitten, undoubtedly so that she cannot be made to talk. Kittens do not talk. She also scampers off to Ryan, who regards her with considerable trepidation, and unhesitatingly bounds into his cringing lap. Beckett rises, stalks over to him, and plucks Petra out of his lap before he can pet her. "No," she says firmly to the kitten. "No playing unless you say sorry to Auntie Lanie."

The kitten attempts a growl, finds that it isn't nearly growly enough, changes to a cub and tries again. Beckett greets these attempts with a full-scale parental glare of her own. Petra cowers, squeaks, and changes back.

"So'y," she says. It might be within a mile of sincerity. Possibly.

"Properly," Beckett says firmly.

"So'y." It's close enough.

"Now you can play with Uncle Ryan."

During the disciplinary intermission, Castle has become bored of the caterwauling and has rescued David. David does not share Petra's prejudices. David, in fact, has taken full advantage of Castle putting him down to bounce over to Lanie and Esposito, mew adorably, and endeavour to climb up Esposito's pants in the form of a small black kitten. It is possible that David is as manipulative as his father can be when it comes to the uses of adorability and cuteness. This does not endear _either_ of them to Beckett, right now. She has a sudden ghastly vision of needing to deal with a string of weeping would-be girlfriends. Oh God. He'll be just like Castle. Oh, _God_. Maybe they should all retire to the cabin, from age five – no, from now – till age eighteen. Or twenty-one. Or forty. Oh, _God_.

Lanie looks down at David being cutely adorable and, obviously being as susceptible to kittens as she is to babies and small children, coos in a vomit-inducing sugary tone and picks him off Esposito's pants to fluff him and pet him and generally treat him with completely ridiculous adoration. (Beckett wonders if Lanie surfs the net for all those kitten videos. If so, she'll never let Lanie forget it.) Esposito is rigid and unwelcoming.

Petra is very obviously ignoring Lanie in favour of Ryan. This _you're not my friend_ behaviour will also need to be corrected, but not now. Rather unkindly, Beckett is perfectly happy to allow Lanie to find out what rejection feels like. After all, Lanie just did it to her, and that so-called apology isn't really good enough.

And then, of course, there is the problem of Esposito.

"Can you manage without me for a while?" she whispers to Castle.

"I guess. Why?"

"I wanna deal with Espo. Lanie's come round, though she owes us both a better apology than she's managed; and Ryan's come through just fine. I'm glad we didn't bet on him fainting, though. I'd have lost."

"Yep, and you know what that means," Castle says wickedly. "It means I get to do whatever I like with you."

Beckett blushes, and wriggles just a tiny little bit. "But we didn't bet so I didn't lose," she says. Of course there is no hint of disappointment in her voice, so it's ridiculous that Castle is regarding her with a naughtily knowing look and darker eyes. She sharpens her tone. "I can take him out or the study."

"Up to you."

Very shortly after O'Leary's first babysitting experience the open bookshelves had been backed by an architectural glass wall, to prevent the ever-more-mobile twins going straight through them and creating even more havoc than usual. Therefore the study is now relatively private, but Beckett will still be able to see if matters – that is, the twins (probably only the twins, but that's not a sure thing) – are getting out of hand.

"Esposito, on me," she raps. Esposito, completely brain-fried by both his introduction to unreality and by Beckett's infuriated reaction to his behaviour, answers as he always does, and follows her to the study. She shuts the door firmly.

"Are you going to rat on us?"

"No! But you're not _human_!"

"I'm still me!" Beckett yells back. "I'm the one who went into bat for you when you came into the Twelfth and were getting hassle from that ape. I'm the one who was in a hundred tight situations with you and had your ungrateful back all the way. I'm the one who saved your miserable ass when you nearly got thrown out for getting rough with that guy who killed the kid. And now you _dare_ to dump me because I'm _not human_? I'm a fuck of a lot better person than you are. Because I know what's griping your lousy guts."

Esposito opens his mouth. Beckett rolls right over him in a wave of fury.

"I know what your beef is. You found out that Castle and I are bigger badasses and more dangerous than you and you can't handle it. You got this idea that Castle's soft 'cause he was never a cop and doesn't carry a gun and he does most of the home stuff and baby wrangling, and now you found out that he's not and you can't get past it because he's tougher than you. Well, the hell with that. You can take your petty jealousy and shove it."

"'T ain't that," Espo says miserably.

"Yeah, right. It is that. It's obvious. You can get over it or get out."

"'S _not_." He cringes. "It… um…"

"Spit it out," Beckett says impatiently. "I could be playing with my kids."

"You're all _shapechangers_. Nahaul."

"Na-what?"

"Nahaul. Brujo. Witches and wizards. They're" –

"Oh, for Chrissake, Espo. You're going to say we're evil? You've known me for all these years working together and you believe that _shit_? I never had you pegged as superstitious."

"No, but… my abuela, she told me all the stories an' now it's _real_! So if you exist there might be others who ain't cops…"

Beckett looks at Espo's tight, pale face and clenched fists. Tougher-than-anyone Espo is genuinely scared.

"I've never met a single other one. Ever."

"So who changed you?" Espo asks, which is a fair point.

"I went looking for him. He – it was like he'd never existed. He was Russian. I'd never found _anyone_ else."

"But you changed Castle."

"Yeah, and you know Castle. He bitched and whined till I agreed." She glares at Espo. "And the twins were born this way, so stop looking like that."

"But…"

"But it's real. Just because your abuela told you scary stories you can't look at the actual _evidence_ in front of you? Call yourself a detective? What's your evidence that there are bad shapeshifters out there? The National Enquirer?"

"What about all those reports of…two… big…" Esposito looks at the sentence unrolling in front of him. "Aw, _shit_. That's you."

"And it's all lies. Yeah, we do go out to Central Park. But we've never killed anything but squirrels and wildlife. We've never touched a human." She doesn't mention scaring them, because that would be a major lie. They've – she has – scared a lot of lowlife humans. "Right. You've got till you come out of this room to straighten yourself out. After that, you either go with it or you leave, and you don't come near my kids again. Capisce? Oh – and you'd better put in for a transfer, too, because you won't be able to work with me if you can't get past this."

"But… we've been a team for _years_."

"It's not me who's screwing that up. I've been like this since before you ever met me. It's not me, it's you."

She stomps out.

Back in the main room, Castle is playing with Petra, rather tentatively assisted by Ryan. Lanie is petting kitten-David, who has discovered that the way to Lanie's heart is to be small and cute. David likes being fussed over and adored, which is the way to an easy and comfortable life in which everyone loves him. It's disturbingly well-thought through for a toddler. Of course, given that this is Castle's child, it's probably instinctive. He's far too like Castle for Beckett's comfort.

Castle looks up and assesses the situation. He opens his mouth, but all that emerges is "Ow!" as Petra bounces over him and attacks his ear. "No pulling my ears."

"No?" Petra cheeps. "Mama do it."

"That's different. You don't do it."

Petra looks very speculatively at her father, and receives a firm look straight back. She turns into a cub, and disports herself in Ryan's lap. When this doesn't immediately result in petting, she turns back.

"Wan' hug, Ry!" she demands.

"What do you say?" Castle says.

"P'ease." She flips back. Beckett watches the smooth transition in despair. Of course they couldn't be so lucky – if it had only been difficult, she might not do it so often.

Ryan ruffles her fur and smooths it again: repeats until Petra cuddles down with her head on her paws and starts to emit a baby purr. She looks very smug. Possibly this is because she's up past her bedtime and has worked out how to defeat the stairgate. Beckett thinks bleakly that they'll need to get a double height one which leans over at the top. Or the equivalent of prison wire.

David spots his mother and bounces out of Lanie's affectionate (and possibly smothering) petting. He bats at both Beckett and Castle, who exchange glances.

"Are you two going to freak again if one of us changes?"

"Try not to," Ryan says, with only a minor tremor in his voice. At least he's truthful.

"Er…" Lanie says, "are you sure about this?"

"Can't you take it?" Beckett says irritably.

"Yes," but it sounds very doubtful. Beckett ignores the doubts.

"You or me?" she asks Castle.

"You. David'll want to play if I change and it might be nice if they went to sleep soon."

"Okay."

Beckett shifts shape and regards the assembled group dyspeptically. This doesn't stop both her children mewing happily and bounding all over her. She growls. Petra peeps at her panther parent and with some indication that she is _also_ Castle's child decides, suicidally, to pounce on Beckett's flicking tail. Beckett growls much more scarily and everyone shivers, even Castle. He, however, stretches out and strokes her spine. She glares at Petra, who backs off, changes, and humphs. She sounds remarkably like a baby version of Beckett. David changes for the sole purpose, it appears, of looking saintly.

"Don't sulk."

"Wan' Mama to play!"

"Don't bite her tail, then. It's naughty."

Petra peeps at her father. "Bite your tail?" she tries hopefully.

"No biting anyone. Biting is naughty. If you bite, time out."

"Petra play chase!" David says, sneezes, turns back into a cub and bats at his sister, who turns into a cub and bats back, much harder. David meeps, and retaliates. Beckett puts her head on her paws and watches the pair chase each other round the floor, hiding behind cushions and pouncing on each other.

"Shall I put the pizza on?" Castle asks. Beckett nods, and continues supervising, rumbling warningly if the cubs get too boisterous. She has noticed that Espo still hasn't come out of the study, though he's watching through the glass, and hopes that he's trying to get over himself.

* * *

 _Thank you to all readers and reviewers._

 _Reviews were non-answerable for a couple of days, but I think I've caught up. If I've missed you, apologies and thanks._


	6. Chapter 6

**Chapter 6**

Lanie and Ryan are thoroughly absorbed in the cute, playing cubs: "helping" one or the other by moving the cushions to confuse them, when Esposito finally exits the study. Beckett is _almost_ sure that the imminence of pizza and possibility of more beer is not his driving motivation, but the hitch in his progress when he sees her isn't terribly encouraging.

He sidles in, doesn't make it hugely obvious that he's giving Beckett room, and sits back down on the couch. The tension in his gripped hands doesn't bode well.

And then the cubs, squabbling and fighting and growling at each other, tumble over Esposito's booted feet as one tries to bite the other and achieves only his bootlaces – and Espo picks one up in each hand and produces an almost Beckett-worthy glare.

"No biting."

The cubs look at him and try to wriggle away. That failing, Petra growls. "I'll arrest you," Espo says. Petra doesn't look impressed. David mews. Coming from a panther, it sounds a bit silly, and Espo grins. "Handful of trouble, you two." He dumps them in his lap and ruffles their necks. Beckett relaxes, and as she does, Espo does, though the true test will be Castle.

The twins scramble down from Esposito, who manfully controls his wincing as their claws get rather too close to sensitive areas – serves him right, thinks Beckett, who is still a tad irritated with him. Castle is fussing in the kitchen, probably so that he can avoid the three supposed friends' discomfort.

Not long later, Castle returns. "Five minutes or so," he says, referring to the pizza. "I think we should put them back to bed."

Beckett stands up and shakes her paws out, then shifts back. "Yeah. One each. I'll take Petra." She swoops on her furry daughter in tandem with Castle catching his son. They are not popular. Both children achieve toddler-form and make their displeasure very loudly known. The echoes are still bouncing from the loft walls as they are carted upstairs and deposited in their cot.

"Time to sleep," their parents say firmly.

"No!"

"Yes. Night is for sleeping." David yawns widely, which infects Petra. They cuddle down together, and a minute later their eyes have closed. Neither parent is confident that this will continue, but they might at least get their dinner in peace. The door is firmly shut and they return to the family room just as the oven starts to sound to signal that the pizza is done.

Everyone sits down to the pizza and beers. This, conveniently, allows everyone to stay silent on the grounds that they are eating or drinking. Lanie is sneaking peeks at Beckett, and occasionally Castle; Ryan is simply scarfing down food as if he's never eaten in his life before; and Esposito has retreated into unusual thoughtfulness. However, eventually the pizza is all gone, and there is no excuse for avoiding the elephant (well, two big cats) in the room.

"I bet Gates wasn't impressed," Ryan says.

"Damn straight," Castle agrees. "I never knew there were so many saints."

"She lost her cool?"

"No, she just got icy. Gates is not into kittens. Or panthers." For some strange reason everybody in the room hears _just like the rest of you_ at the end of Beckett's sentence.

"But they're so cute," Lanie says. Espo makes gagging noises. "How could she not love them?"

"She's not a crazy cat lady like you are?" Lanie glares at Esposito. "What? You're all over those YouTube cat videos."

Beckett sniggers. Castle smirks.

"At least I like living things. You probably get your rocks off with Guns and Ammo monthly."

Espo goes purple. Ryan grins.

"If either of you two wake the twins you're taking them home," Beckett notes coolly. "And might I just add that they wake _early_ and want to play and eat breakfast, and complain very loudly if it doesn't happen."

Voices are instantly lowered. No-one wants the twins woken, except possibly Lanie, who quietens under the weight of peer pressure.

"So you been like this since nineteen?" Espo says, less aggressively than earlier. "Musta been weird."

"Yep."

"An' you found out" – Espo counts up, looking at Castle – "musta been before Halloween an' that vampire case."

"Yep."

"An' you whined till you got to be one too."

"Yep," Castle says smugly. "And I did."

"Couldn't stand the whining any more," Beckett snarks.

"You wanted another shapeshifter too," Castle says insinuatingly.

"TMI, bro."

"But you never told us."

"I never told _anyone_. You think I wanted to be a lab rat? We've been round this loop. Suck it up and deal."

"Change again, both of you?"

"No petting. We don't do petting," Beckett says very firmly, directed mainly at Lanie, who pouts. "We'll do it _once_ , for a few minutes, and then it's _over_."

They all traipse away from the table, and once more the two black panthers appear, to muffled squeaks. This time there are no horrified yells, however.

"Definitely badass," all three agree.

"You sure you couldn't do that in Interrogation? We'd never lose another case."

"No," Beckett says, back to human. She pets Castle gently, who rumbles and stays feline for now. Everyone seems to be more or less cool with it, finally.

"Can't say it's not weird," Ryan pronounces, "But I think it's pretty cool. We'll help you keep it secret."

"You and Gates. She's doing a _home visit_ tomorrow, just like she's moonlighting for Child Services."

Everyone's jaw drops. "Oh, Christ," is the main flavour of reaction, followed by sympathy.

"You'd better have another beer."

"We'd better emigrate," Beckett mutters.

After that the evening contains a lot of beer.

* * *

"I thought you said we weren't going to tidy up?" Castle says, as Beckett dashes round dropping toys into a box which the twins promptly empty again.

"It's Gates," she answers, which explains everything. "Anyway, I thought _you_ said we weren't going to do food and wine." Both are on the dinner table, out of the way of toddlers. They have already eschewed any tablecloths, fortunately before disaster had occurred. Even a kitten's weight would be enough to pull it from the table, as they had found. To the twins, cutlery hitting the floor is a delightful sonata. To the adults, it had been the toll of doom. Well, _another_ toll of doom. Parenthood seems to be one long toll of doom to civilised life, albeit they wouldn't be without their tiny terrorists.

"Beckett, it's not working. As fast as you pick up, they get them out again. Just leave it."

She sighs. "It's like being inspected."

"Her problem. Not ours. Have some wine."

Castle does the best thing possible and pours the wine, following up with a comforting hug. Naturally, this prompts the twins to toddle over and copy him. Beckett regards her legs, currently decorated with a momentarily-adorable infant each, and manages a weak smile.

"It'll be okay. Well, it can't be worse than Monday. At least she knows what she's seeing," Castle notes.

"I wish I'd never suggested telling anyone. Your mother was okay, but Alexis freaked and the other three were absolutely dumb" – Castle nudges her – "a- about it. I thought everyone would deal, and nearly nobody can handle it."

The twins go back to creating minor mayhem.

Castle pats her gently. "We agreed. We didn't have a choice. Anyway, let's take them up to the cabin where there's no-one around at all and have fun. You know how much I love chasing you through the woods."

"They'll need therapy if we do that," Beckett mutters. "And we can't leave them alone."

"Babysitter."

"There aren't any. And we are not taking Dad or anyone else."

Castle droops. "No chasing?"

"No. That's the joy of parenting," she says sardonically.

"Now that everyone important knows, though, we've got a wider pool of babysitters."

Beckett growls.

"Too soon?"

"Yep."

Before the squabble can escalate, the door sounds. Captain Gates, regrettably, is right on time.

"You open the door," Castle bleats.

"Why me?"

"She's your boss."

"Coward."

"Yes."

Beckett goes to open the door in a way which strongly suggests that the discussion has not been finished. Castle ensures that he is positioned in order to prevent any escape attempts by either twin.

"Good evening, Detective Beckett. Mr Castle."

Much to Beckett's amazement, Captain Gates produces a bottle of wine. Castle takes it from her with thanks and, as he reads the name, respect.

"Shall I open this one for all of us?"

"That would be very pleasant."

Beckett just wants the alcohol. Unfortunately she can't simply down her glass in one. Even more unfortunately, she still doesn't have a plan, still less one which she and Castle have discussed or agreed, as to what they want from Gates. She hopes, in a straw-clutching way, that Gates won't ask.

Wine is poured, and Gates seats herself on the couch. Castle and Beckett exchange terrified glances. Gates pretends not to see them. Beckett thinks fastest and sits herself on the floor near the children. She doesn't like the informality at all, but she wants to sit with Gates even less, and this way she has a built in excuse. She's ready to step in as soon as the twins start to fight. With a bit of – tonight, anyway – good luck – or normality – that'll be in less than five minutes.

Castle flings Beckett a look equally composed of panic and _how could you do this to me_ (easily, Castle. Really, really easily) and then sits down very tentatively at the other end of the couch from Gates.

The twins suddenly notice the extra adult. They give up their incomprehensible game to toddle over and examine this new plaything. Gates examines them right back. David bats his eyelashes, which has no effect whatsoever. Gates is impervious to cute looks.

"Who that, Mama?"

"Captain Gates. Remember, she's Mommy's boss. You saw her on Monday."

David thinks, and continues to regard Gates with limpid blue eyes which are very similar to his father's – except they don't contain the suppressed terror of Castle's. Petra has no such issues of memory. She favours Gates with a hard stare very reminiscent of her mother (who has rarely dared to use it on Gates) and pulls a thought from her toddler memory. Unfortunately, it is not a happy thought.

"Cross lady."

Beckett puts her head in her hands and considers becoming Onyx and then hiding. Petra can be _astonishingly_ unhelpful to affairs.

"No," Castle says. "Captain Gates. Say that, please."

"'Ates."

"Both words. Captain Gates."

Petra makes a mangled effort. Beckett peeks between her fingers and observes with dumbfoundment that there is a tiny twitch at Gates's mouth.

"Captain Gates," Gates says clearly. "What's your name?"

"Petra!" She toddles closer. "I a cat. You a cat?"

"No." Petra pouts. "Show me the cat?"

Petra regards her dubiously, and then decides to comply. She becomes a kitten, and is instantly distracted by the tassels on Gates's sensibly flat shoes. Gates reaches down, before the tassel can be chewed, tugged, clawed or otherwise stalked and killed, and picks Petra up to plop her in her lap and, despite her stern demeanour, allow her hands to fuss over her. David looks at Petra receiving attention and squeaks.

"Me too!"

"Show me your cat."

David does. Gates plops him in her lap too, and then examines them one by one, carefully.

"I see they take after their parents," she says. Somehow it doesn't sound as if it's wholesale approval, even if she is petting them. The kits are emitting their baby purrs. "They have each of your eyes. I suppose that allows you to tell them apart?"

"Their personalities would do that," Castle points out. "They're quite different."

"Mm."

Castle falls into the trap he _always_ falls into when faced with Gates, which is thinking that talking will help.

"Oh yes. Petra is very like Beckett. David's just like me. It's amazing, really. I mean, Alexis is nothing like me or her mother" – Beckett makes a slight noise – "well, absolutely nothing like Meredith though I suppose in some ways she is like me – but the twins really are mini-us. David's friendly and happy" –

"And goes in for death-defying idiocy" –

"That's not fair – and Petra is very focused. And she's got the Beckett glare." Beckett demonstrates the glare, aimed firmly at Castle.

Gates looks at Beckett. "Detective Beckett, are you sure that introducing a _second_ Mr Castle to the world was a good idea?"

"It's not like you get to choose what you get," Beckett points out. "I'm quite happy with two Castles."

"And I'm delighted with two Becketts," Castle puts in.

"I imagine you are," Gates says dryly. "As am I. That way there is, at least, some hope that you might be kept in check." She lets that sink in.

Petra and David are beginning to squabble in Gates's lap: swiping at each other with small paws and small claws. Gates picks them both up and glares coldly.

"Behave," is all she says. Even Petra cowers, and does not try the glare.

"Are you _sure_ you wouldn't be their nanny?" Castle says.

"Mr Castle, there is not enough money in the _world_ for that to be a tempting offer."

Petra mews, and jumps down. Shortly she is a toddler again, and toddles back to Beckett to give her a sloppy kiss. Beckett cuddles her.

"Mama be cat. Mama play with me."

"I should like to see the cat. Not the panther, note." That's an order, if ever Beckett heard one. She gives her wine glass to Castle to keep safe and becomes Onyx. Petra bounces delightedly and becomes a kitten again for the sole purpose of chasing Beckett's gently waving tail.

"I see," Gates says. "That is certainly a more publicly acceptable form." David bounces out of her lap and starts to stalk his mother. "And you, Mr Castle? I take it you are also capable of being a cat?"

"Yes."

"Show me."

Castle shrugs, becomes the cat, and is instantly charged by two hyperactive fluff-monsters. Unlike Beckett, he play-fights with both of them, and shortly happy mew-squeaking fills the loft.

"Please change back, Detective." She does. "Now, sit with me, out of the way of the children." Clearly, that includes Castle.

How is Beckett doing exactly as she is told in her own house? This is unfair. Gates can't give her orders here.

"The cat forms are perfectly acceptable."

"I was aware of that," Beckett says dryly. "Our issues are not around the forms. Any of them. Our _problem_ is that the twins change at random and are too young to understand that they shouldn't."

"I see."

"If they'd just stayed synced to me rather than frightening my father into fits it would have been fine."

"Your father?"

"Dad came over on Saturday as usual and the twins chose that day to prove they could change without me."

"I take it this was a considerable surprise to your father?"

"You could say that."

"And to you." Gates almost sounds sympathetic. "Children are difficult enough to manage without adding extra complications."

"It wasn't complicated when they were synced to me. Now we can't even take them to a playground."

"Hmmm. Difficult."

 _Tell me something I don't know_ , Beckett thinks bitterly.

In the background the twins are still stalking Castle, and are now cubs again; still not nearly as big as Castle's Maine Coon cat form but enthusiastically pushing him around. When they go too far they get a relatively gentle swat. When one pounces on his tail and chomps down, however, Castle yowls, returns to human, and gives her a severe telling-off – at least till David tries the same on his fingers, when both of them are separated and equal tellings-off and time-outs administered. Two little black noses scrunch; two sets of whiskers droop, and both of them lie down in an attitude of miserable penitence. It's entirely insincere, since they will create havoc again just as soon as time-out is over.

Castle regards Gates from his parental perch on a floor cushion.

"This is all exceedingly interesting," she says. "May I have some more wine, please?"

Castle refills everyone's glasses.

"Now, please change yourselves into panthers. I can't help unless I have all the evidence."

Wine glasses are set down, and Castle's massive feline appears. Beckett follows. The twins meep happily until Beckett growls at them and they are reminded that time-out is not quite over. Gates is commendably cool at the sight. How unfortunate that she was only intimidated on seeing them for the first time.

"Hm," she says thoughtfully. "You're a lot bigger than I expected."

Castle taps the twins gently to signal the end of time out, and they bounce up. Beckett changes back, to protect her tail.

"So are they."

"They're still kittens."

Gates regards her disbelievingly. "How can they still be kittens at two years old?"

"I don't know. They should be full-grown, as cats, but they're not. I try not to think about it. It gives me headaches."

Gates nods, slowly. "I see. The human genetics are driving everything. Hmm. This is a pretty problem you have provided, Detective Beckett."

"Yeah." Beckett catches a glimpse of her watch. "Um… we have some food, and the rest of the wine. We need to put the twins to bed, but if you didn't mind waiting…"

"I shall be happy to." Gates almost blushes. "I would be happy to help with bedtime, if you didn't mind."

Beckett gapes at her. "You want to help?" That's flabbergastingly unlikely. In fact, that might win the prize for most unexpected statement of the century – and with Castle around, that's a very high bar. _Gates_ wants to help put two terrorist toddler shape-changers to bed? _Gates_ , scourge of criminals and cops alike? _Gates_?

Gates presents her with a very still face. "I have no children, Detective."

Beckett suddenly understands much better, and tactfully says absolutely nothing at all, though the Gemini dolls collection now makes sense.

"If you want," she says. "It can get a bit messy and splashy, though." She looks at Gates's attire. "You might want an apron. I usually do."

"That might be wise."

Beckett ruffles Castle's neck fur, and he changes back. "Bedtime for the terrors," she says. "Gates would like to help." Castle gapes, and then snaps his mouth shut.

"She would? After meeting them?"

The twins are still stalking each other and the cushions, pouncing and playing. That means that getting them bathed, their teeth brushed and them into bed is likely to be troublesome.

Beckett has reckoned without the Captain Gates effect. The twins do not wish to change back to toddlers – until Gates fixes them with a basilisk glare and simply says, "Obey." They do. Quickly.

Petra casts Gates a speculative look, which sits rather oddly on her babyish face. She toddles up, and raises her hands to be lifted up. Gates is momentarily nonplussed, until Petra demands, "Up," in a tone that Gates really ought to recognise but fortunately, not being expert in toddler-translation, doesn't notice is exactly equivalent to her moments-earlier _Obey_.

"What do you say?" Beckett says. Castle is absorbed in capturing a giggling, scurrying David.

"P'ease up," Petra says, with an adorable glance through her long lashes which entirely belies the Ghengis Khan-ate tone she had just used. Her still-chubby hands reach for Gate's jacket. Gates, after an instant's indecision, swings her up, only wobbling slightly at the unexpected weight. Petra has density. Beckett thinks it's from bouncing round as a feline most of the time: she's probably developed more muscle than one might expect.

"Where do I take her?"

"Upstairs. Follow me."

* * *

 _Thank you to all readers and reviewers._

 _Hawkie, the squicked reaction is the result of a number of authors making it very clear that vampirism and shapeshifting tend to be passed on via... um... intimate relations._

 _Rune, the twins are only just two._


	7. Chapter 7

**Chapter 7**

Beckett starts the bath while Gates amuses Petra. That is to say, Petra presents each toy for Gates's inspection and babbles at her (definitely _at_ , not _to_ : no answers are required) to instruct her in the correct method of playing, while David tries to intervene and is consistently ignored or silenced. By Petra. Petra, it appears, has decided that Captain Gates is her personal possession. Gates, luckily, has not yet worked this out.

"Why not cat?"

"Sorry?" Gates queries. Toddler translation is a learned skill.

"You not cat. Why? Mama a cat. Dada a cat. Dav'd a cat." Petra thinks. "'Anie not a cat. Ry not a cat."

"Ry got no tail," David says pityingly. "Poor Ry."

"'Anie wouldn't play," Petra says, remembering her sense of grievance. "'Anie not nice." She pouts.

"Ry shout," David adds. He giggles. "Ry scared. Silly Ry."

During this artless and entirely unhelpful conversation Gates has developed the closest thing to a smile anyone has seen upon her face, although it would be true to say that it most closely resembles the smile on the face of a hungry tiger. Gates, Beckett remembers dismally, was a shit-hot investigator before she took on the Twelfth, and it's pretty clear that she's drawing a number of conclusions.

"'Spo cross. Mama cross too. An' Dada."

"Gramma played."

"Lex not a cat. No fair."

"Why you not a cat?" the twins ask again.

"Most people aren't cats too."

The twins look blankly at her. " _Not_ cats?" Petra says, disbelievingly. It sounds very like a baby version of Interrogation Beckett.

"No. Just you four."

Listening, Beckett winces. This is one time she wishes Gates didn't give dead straight answers to questions.

"No cats?"

"No."

"Not true. You _wrong_."

"You, David and your parents are cats too. No-one else."

"No!" Petra yells. "More cats. Want cats!"

Gates, for the first time ever to Beckett's knowledge, is left unsure what to do. Despite her strong desire to watch Gates flounder, she steps in.

"Petra," she says quietly.

"Mama," the toddler wails. "She not nice. She said no cats." Petra's face is crumpled. " _We_ cats."

"We are cats, sweetheart. You, me, David and Daddy. But no-one else is."

"No cats?" Petra sobs.

"Just us." Beckett cuddles Petra's miserable little body, and manages an arm for David, who ambles up to be hugged too.

"Why?" David asks.

Beckett would rather Gates wasn't there for the next bit, but fortunately she can sense Castle (who has turned off the bath, about which she'd forgotten) arriving to sit next to her.

"Magic," she says.

"Bath time," Castle says, "and while you're splashing I'll tell you a story."

David scampers over to his father, who sweeps him up and twirls him round. He squeals delightedly. Beckett wishes for earplugs, but not as obviously as Gates does.

"Story?" Petra whimpers. Beckett pats her consolingly.

"Yes, story. When you're in the bath."

"Story 'bout cats?"

"Yes, little kittens. A story about cats."

Petra drips out of Beckett's arms, and is swept up to join her brother in Castle's arms. He takes them off to be bathed.

"Magic?" Gates says, with a very cynical inflection. "I thought better of you, Detective."

"Have you got a scientific explanation?" Beckett bites back.

"Mr Castle believes in magic and indeed in many forms of insanity or props for the feeble-minded. I do not."

"Okay, explain this. I was bitten by a Russian fellow-student who turned into a panther and bit through my jugular one Hallowe'en under a full moon. When I tried to find him it was impossible. I thought – just like you do – that it was just a stupid, drunk student dream. Right up till a year later when I was in a dangerous situation and turned into a _cat_. Have you got a _scientific_ " – the edge on that is lacerating – "explanation? Or for the fact that the same thing worked on Castle?"

"Not at this moment."

Gates leaves before she has to admit Beckett's point, following the shrieking to the twins' bathroom, where they are battling with rubber ducks while Castle cleans them up.

"Did you have a story?" she asks.

"Yes. Dada tell story."

David manages to get in a surreptitious splash at Petra as he's talking. Petra, still in unhappy temper, retaliates with a swipe of duck, which connects and produces an angry yell.

"No hit me!" he shouts.

Petra turns into a cub, discovers again that the cub doesn't like water, changes back and bawls. Castle scoops her out and into a towel, and hands her off to Gates.

"You can dry her," he says blandly, "and if you can stop the noise that would be nice too." Gates regards him with an acidulous stare, and regards Petra's red, screwed-up, wailing face with displeasure.

"Shush," she says sternly, though her hands soothe and gently rub Petra dry. "That's not necessary." Petra squawks. "No. Stop the noise." Gates spots a diaper and a sleepsuit, and achieves Petra's insertion into both with a minimum of fuss. Castle raises an eyebrow.

"That was pretty efficient."

"Diapers and sleepsuits hardly require a lifetime's training in investigation, Mr Castle. After all, almost everyone appears capable of managing them." Her tone might be indicating _even you_.

Castle dries David out and whisks him into his nightwear.

"Why did you insist on becoming a shapeshifter?"

Castle clamps his lips shut on _none of your damn business_ , and instead says, "Not in front of the twins."

Beckett appears. "Teeth," she says generally, and reaches for the bundle of Petra which Gates is holding. Gates is quick to hand her over, and exits the bathroom with more alacrity than style. Teeth-brushing is clearly a step too far. It's a step too far for Beckett, too, but it has to be done. Mostly, she doesn't get bitten. Now.

"Open wide," she says to Petra. Petra clamps her mouth shut. Beckett presses on her cheeks and her little white teeth appear. Brushing occurs. Screaming also occurs. As Castle deals with David, stereo screaming occurs. It has no effect on either parent.

Gates has retired to the twins' room and is examining the bookcase as if it were a CSU report. This is not reassuring. She regards the board books and ranks of bright covers without expression. Presumably they are far too cheerful and childish for Gates's liking.

Beckett is therefore utterly astonished when Gates removes _The Very Hungry Caterpillar_ and says, in coolly authoritative tones, "If you don't mind" – that's not a request, Gates, it's another order – "I should like to read them a bedtime story."

Now Beckett really needs that wine. All her assumptions are upside down. Castle looks equally boggled, but in typical Castle fashion doesn't wait before he opens his mouth.

"You want to read them a story?"

"Yes, Mr Castle."

"But… but…."

"Do you not think I am eminently capable?"

"No, but… um… they don't know you and one of us has always read them a story and…um… have you ever _read_ a baby book at all? Because it really doesn't seem like something you'd read and reading out loud is completely different – _ow_! Beckett, what was that for?"

Beckett had elbowed him hard, on seeing the small changes in Gates's frozen expression.

"Yes, you can," she says to Gates. "They like that book." She drags Castle out of the room. "Just let her do it."

"But Beckett," he whines, " _we_ do that."

"She said she'd never had children," Beckett says very quietly. Castle's eyes widen.

"Oh."

"So let her do it. Please, babe?"

"Okay. Um… why don't I go and pour more wine."

"Yep."

Downstairs, Castle refills everyone's glasses with the last of the bottle Gates had brought, and waits. Shortly (the book not being long) Gates arrives. Castle ambles up to check the stair gate, and, finding it firmly shut, returns.

"We have some snacks," Beckett says.

"Thank you."

There is an awkward silence, which is not filled by the eating of some snacks.

"Who is aware of your" – Gates clearly searches for an appropriate word – " _issue_? I infer that Detectives Ryan, Esposito and ME Parrish are informed – your son's verbiage is as prolix as that of his father – but to whom else from your list have you already spoken?"

Castle is too busy grumbling to answer.

"Alexis and Martha. My father knows. O'Leary has known since just after they were born." Gates raises an eyebrow, commanding an explanation. "We were partners when I was a rookie. He said he'd always suspected, and took the opportunity to find out when we were too tired to be careful."

"How intelligent of him," Gates says approvingly. Beckett growls. "I see."

"Everyone has been told not to say a word to anyone."

"Naturally," comes dryly back. "Do you believe that will happen?"

"Yes. _My_ friends" –

"And my family," Castle inserts –

"have my back."

"Mm."

"If yours don't," Beckett snaps, infuriated to the point of forgetting that Gates is her boss, "you need better friends."

"I am as confident of my friends" – Gates actually has friends? This is front page news – "as you appear to be of yours. I trust that you will not be disappointed."

"I won't be." Beckett drills a glare right between Gates's cold eyes.

"I see that your daughter has inherited your temper, Detective."

Beckett's own temper is running high. "Are you going to continue sniping at us in our own home or did you intend to provide any help?" she enquires bitingly. "Because if you can't help, just stop now. We'll find our own solutions." Castle gulps, which is no help at all.

"I do, in fact, have one idea. Your children are as active as any, which is, no doubt, inherited from their father. I have observed that since your children were born you have not had as much time to exercise, although your fitness levels remain unmarred. I understand that Mr Castle's books are extremely successful" – Castle definitely hears _God knows how_ – "and that he is, therefore, extremely well-off." Gates doesn't seem to approve of that. "It therefore escapes me why both of you appear unable to think about using some of that wealth to address this problem. I have become aware" – she doesn't specify how, and Beckett doesn't dare ask – "that there are facilities where small children may play in a soft environment."

"Indoor play?"

"That's the term. Surely it must be simple for you to see the possibilities?"

Castle, about to open his mouth on instant response to the implication that they are dumb, suddenly slams it shut again. Beckett regards Gates with a very peculiar expression.

"I see you understand me. I am glad that the unusual problems of your family have not lessened your speed of understanding."

"I see."

"About time. I might also consider that Detectives Ryan and Esposito require some extra training time, which might usefully be undertaken in such an establishment, and I am certain that if Detective O'Leary were consulted he would consider that he also does, and make appropriate arrangements with his own precinct. I leave it to you to work out a suitable schedule and present it to me. Of course, I don't expect it to impinge on your mandated shifts. Nor will I be impressed if you use the precinct gym. I will not encourage your family to attend the Twelfth. My precinct is for police work, not for family reunions."

Castle is bemused. Beckett takes pity on him. "Captain Gates is suggesting that we hire out an indoor play facility privately for our sole use and take the twins to it with Ryan, Espo and O'Leary, to run off their energy." He goggles. She turns back to Gates. "Thank you, sir."

"I still expect you to come up with a plan, Detective. You have until Monday."

No pressure there, then, Gates. Just as Beckett was totally in charity with her, she spoils it.

"I believe it is time for me to go home. Thank you for your hospitality, and presenting me with the facts. I shall try to assist you." She stops. "However, please do not take this as license to employ your other form in chasing down criminals. Your desire to keep it secret should be maintained. I would not be able to assist were other agencies to discover the truth."

She stands up and favours Beckett with a thin smile. "If your daughter were to continue to resemble you, Detective, that would not be a bad way to grow up."

"What about David?" Castle asks.

"If he were to resemble his mother, that outcome would also be highly desirable."

As an exit line, that's unmatchable, which Gates has clearly worked out, since she has exited while Castle is still gleeping indignantly at her back.

"She doesn't improve with wine," he says.

"No, but at least we can take the cubs to an equivalent of a playground."

They sit down and start to plan.

* * *

Beckett is placidly attending to her caseload when she notices Gates summoning Esposito and Ryan. This causes her a momentary trickle of tension, which she shrugs off. Gates randomly terrifies many of the bullpen.

She wouldn't be nearly as sanguine if she had noticed the Captain's door closing. Had she been able to hear the conversation, she'd have been downright appalled.

"Yes, sir?" Ryan says to Gates.

"I wish to talk to you both."

"Sir?" Esposito queries cautiously. Querying Gates is bad for one's health.

"I understand that you were less than impressed by Detective Beckett's family peculiarity."

"Beckett told you that?"

"No. Detective Beckett did not. Her twins, however, do not have her discretion. It was perfectly obvious that you did not distinguish yourselves by your conduct." Both men squirm. "Be advised, Detectives, that any hint of Detective Beckett's privacy being breached will be dealt with, with the utmost severity of which I am capable." They shiver. "I assure you that you do not wish to test the limits of my severity." They shake their heads, frantically.

Once Gates is sure that her ability to reduce all-comers to quiveringly terrified wrecks is undiminished, she allows them a tinge of hope. "You may, of course, wish to assist Detective Beckett with this difficulty."

"Uh, yes?"

"The children require exercise. I have advised Detective Beckett that she requires to maintain her fitness levels, and that she should spend some time in an _indoor play area_ " – that carries considerable disgust – "in order to remain in peak condition. Naturally, this must occur outside training hours and her normal shifts."

"What's that got to do with us?" Esposito asks. Ryan elbows him.

"Don't be dumb, Espo. We're being ordered to go too."

"Very astute, Detective Ryan, but not correct. I cannot order you to do anything in your time off." She smiles very sharply. "But I am sure that you would be happy to play with Detective Beckett's children if time permitted. How old is your daughter?"

"Three," Ryan stammers.

"Hm. A touch young to keep such a large secret, though most people would dismiss it as a child's imaginings."

"Beckett told me not to tell anyone, even Jenny."

Gates's cold eyes flicker, she remembers that Ryan's wife is named Jenny, and blinks slowly, like a reptile. "That is, of course, up to Detective Beckett. You might, however, suggest it." She looks at both men. "You are dismissed."

"Sir," they say, and flee.

* * *

The boys manage to extract Beckett from the bullpen at lunchtime and provide her with a somewhat expurgated download of the Gates commentary, which leaves Beckett devoid of breath or brain to comment for quite some time, which space she fills by eating her lunch. Sustenance taken, she has recovered the power of thought.

"Okay. Um. Ryan, are you happy about Sarah Grace playing with the twins? They're not very… um… careful right now. Um… maybe she should meet them first? And Jenny?"

Beckett is unusually unsure of herself. This whole disclosure thing is getting very complicated. She wishes she'd never started on it, but she has no idea what else she could have done, once the twins forced her hand.

Ryan blinks a few times. "I dunno what Jenny will do – but don't spring it on her like you did on us, okay, because she really won't like that.

"I need to work out a schedule. I need to make sure that no-one interrupts us, even if it's a private hire. We don't want any spectators."

"Could be tricky, yeah."

"Stick your pet mountain in the doorway an' nobody'll notice, 'cause they won't be able to see past him."

Beckett sniggers at the thought. "I guess," she says, and turns to her phone immediately.

"Hey, O'Leary."

"Yeah. Look, wanna come round?"

"No, not to babysit. Beer and dinner."

"Okay. See you about seven? I'll tell Castle."

"Thanks. Bye."

"How come he gets dinner?"

"Cause he's known about the twins since they were barely born."

Esposito humphs. He's a little possessive about how long he's known Beckett, and he hates being reminded that O'Leary was there long before he was, all of which Beckett knows. However, she's still rather ticked off by his behaviour the other day, and not inclined to pander to his prejudices.

She ignores Espo's sulks for the rest of the day, remembers to let Castle know about the change of plan, and departs pretty much at shift end.

* * *

When she gets home, Castle is flatteringly pleased to see her. He is also worryingly relieved to see her. The twins are not in evidence. Noise from upstairs indicates that they are also not innocent in the matter of their absence. Petra is in full voice. David is wailing.

"What happened?" she asks, hugging Castle, of which he seems much in need.

"Uhrugh," he mumbles into her hair. Ah. That bad.

"Mmm?"

"Can we sell them?"

Oh. Really, really bad. Of course he doesn't mean it, but it's code for _they were hell on wheels today_.

"Tell me about it," she coaxes.

"Non-stop tantrums. Well. Not quite non-stop, but when they didn't tantrum they fought. And when they didn't fight each other they attacked me." He displays some scratches, and a set of tooth marks. "Petra bit me. David scratched. So they're both in time out in separate playpens."

"That explains the screaming. Want me to go and growl at them?"

"If you like. It didn't work for me."

"I'll give it a go. And if that doesn't work, I'll try the Glock."

"You can't do that, Beckett!"

She raises an eyebrow. Castle raises a feeble smile.

"You get a drink and look after O'Leary. I'll go toddler-wrangle for a bit."

"Thanks," he says. He looks weary, and much more than a little grateful.

Beckett traipses upstairs to find Petra shrieking at the top of her voice, red-faced and furious, having thrown all her toys out of the playpen, probably at David; and David wailing miserably. David doesn't like being deprived of company.

"Shush!" she says firmly.

"Mama!" David stops wailing and screeches instead. "Out!"

"Wan' out too!"

"Both of you were naughty," Beckett points out. "You hurt Daddy. So you both got time out."

"So'y," David says, unprompted.

"You need to say sorry to Daddy, not me."

"Dada?"

"Yes, to Daddy. No biting or scratching. It's naughty."

"Say so'y."

"Okay."

Petra is remarkably silent. Apologies do not seem to be in her toddler vocabulary. She doesn't seem to be sorry, either. She shrieks again.

"Shush!"

Petra looks at her mother and decides that Beckett means it. This is fortunate for Petra. Beckett does mean it. She _always_ means it. Petra shuts up.

"Petra, you were mean to Daddy." Petra shakes her head.

"No."

"Yes. You scratched and you bit him. That's naughty. You don't scratch or bite."

"Didn't."

"Petra, you did. I saw the marks."

Petra, caught out, turns into a cub.

"Okay. David, you're coming downstairs. Petra, you're staying here."

* * *

 _Thank you to all readers and reviewers, especially the guests whom I can't thank directly._


	8. Chapter 8

**Chapter 8**

Beckett picks up David, to further earsplitting shrieks of panther-cub rage, and carries him downstairs. She would never admit it (except to Castle), but she does love cuddling her snuggly children. She buries her nose in his light-brown hair, and nuzzles. David coos.

"Dada!" David bounces happily on being brought back to Castle. Beckett puts him down. "Dada, I so'y." He manages quite a creditable effort at a run to his father, and grabs him round the leg. Castle, as quick to forgive as ever, swings him up.

"You're sorry?" He kisses the top of David's head. "Good boy." David receives an all-enveloping hug. "Uncle O'Leary is coming to play."

"Lea?"

" _Uncle_ O'Leary."

"Unk," David attempts.

Castle looks over the top of his squirming son to Beckett, who rolls her eyes and starts back upstairs.

"Petra cross," David informs Castle.

"Don't tattle," Castle says automatically.

Beckett reflects that tattling on Petra is not necessary, since, to misquote Wodehouse, it is never difficult to distinguish between Petra with a grievance and a ray of sunshine. Unlike, however, the metaphorical Scotsman, Petra's grievances are made manifest at full volume. Beckett could almost wish for the return of Gates's silencing effect.

"Petra," she says quietly and calmly. Criminals and suspects across Manhattan have quailed at that tone. Petra is not obviously daunted. "Petra, _shush_." Petra, astonishingly, does not _shush_. This is almost unprecedented. She shrieks more, still a cub.

Beckett closes the door, lifts Petra-cub out of the playpen, and herself changes into the full-grown panther. She growls menacingly, and looms over her daughter in a very threatening way, a large paw on her. Instinct takes over, for both of them: though in Beckett's case it's a deliberate strategy to assert the dominance of the pack's alpha female. They've done a bit of reading, to say the least, around that subject. Unfortunately, Beckett can see it being required more and more frequently over the next year. Or the next sixteen years. She suddenly sees her own parents' delight at her choice of Stanford in a whole different light.

Petra's cub instincts silence her, and cause her to roll over and expose her stomach. Beckett growls again, and very lightly nips Petra, making it very clear that she, Beckett, is in charge. Petra-cub whimpers, and looks scared.

Beckett changes back. "Change," she orders. Petra does exactly what she was told, and a damp-eyed toddler appears. "Sit there." Petra does that, too. Phew. "You bit Daddy."

Petra sniffs. Beckett remains unmoved. "'Es," eventually emerges, in a very small voice.

"Why?"

There is a stream of miserable commentary in toddler-speak which Beckett's well-honed investigative skills and interview technique manages to resolve into _David got all the fun_. Beckett is sure this is not true. She waits. _It's not fair_ occupies most of the next few minutes. She waits some more. _Don't like David_ arrives. This complaint occurs every time David gets his fair share of whatever is going on. Finally the whole story emerges. Petra wanted to play with Castle without David, and wasn't allowed to.

"You were naughty," Beckett says firmly. "You and David share Daddy. No biting and no scratching. Both of you were wrong. You need to say sorry."

Petra looks resentfully doleful.

"No. No sorry, no playtime. Just bedtime."

"But," Petra starts, catches her mother's eye, and thinks better of a sentence that almost certainly continued _David's getting playtime, no fair!_ Beckett waits some more, and hears noises of the front door opening. So does Petra.

"What that?"

"Not relevant," Beckett says to her. "If you won't say sorry to Daddy, it's bedtime." Just like usual. They are very consistent about discipline. The twins, even at two and with a limited vocabulary – or a limited _comprehensible_ vocabulary – argue like lawyers, and the slightest hint of an inconsistency is pounced upon.

"I say so'y," Petra finally concedes.

"Okay. Come on, then." Beckett swings her daughter up, cuddles her, and takes her downstairs, where, as she had thought, O'Leary's massive presence is occupying the room.

"LeLe!" Petra screeches. Beckett keeps a tight hold of her, which unfortunately means that she can't cover her ears.

"What do you say to Daddy?"

Castle takes her. "So'y Dada." Petra follows it up with a sloppy kiss. "Dada better." Ah. A hint that there might be a possibility of civilised behaviour – in a century or so. Castle gives Petra a hug and kiss in return and then puts her down. She makes an instant beeline for O'Leary, and scrambles up to smother him in toddler hugs and even sloppier kisses than she'd bestowed on her father. Probably not incidentally, this prevents David doing the same.

"Share, Petra," Beckett says meaningfully. Petra casts her mother a glance which is clearly assessing the risks of disobedience, receives a hard stare in return, and moves enough to allow David to join her. O'Leary's mien acquires a small tinge of terror, despite his long acquaintance with the twins.

Beckett snuggles up to Castle, and watches the O'Leary climbing frame be bounced and clambered upon by the six separate personalities of their twins. O'Leary is generally fairly sanguine about it, though he plucks Petra-kitten from his shoulder when she starts to bat at his ear, petting her with a sausage-sized finger. David pushes in on the act, changing, Beckett notices in despair, without a sneeze.

"So what's the occasion?" O'Leary rumbles. Both twins meep at the bass vibration. Petra purrs. David essays a semi-growl, trying for harmony and achieving only a collective snicker from all three adults.

Beckett exchanges a look with Castle. "Um… as you might have noticed, the twins aren't synced to me any more."

O'Leary blinks. "Oh boy," he emits. "I hadn't… oh." He looks properly at the mixed bundle in his lap. "Oh boy oh boy. That ain't good news."

"That's an understatement," Castle says dryly. "So we've had to tell a few people."

O'Leary's massive mouth drops open, and he acquires an aggrieved expression. "Tell people? You threatened to kill me if I ever let on."

"Yeah. Well. If they hadn't decided to desync in front of my dad on Sunday we'd never have told anyone." O'Leary blinks again, and closes his mouth. "So we have to. We can't take them to the playground, even."

"Slide!" David squeaks, suddenly human. O'Leary obligingly extends his tree-sized legs, and David slides down them. Petra, possibly exhausted from her earlier tantrum, stays curled up as a kitten under one ham-hand. It's so nice to see her quiet and peaceful that Beckett doesn't even comment. David bounces up and down the O'Leary slide and doesn't get in the way of conversation.

"Guess that's a bit of a problem."

"Yeah. So we thought we'd better tell some people." O'Leary wiggles his hedge-eyebrows, inviting her to continue. "Alexis and Martha, Ryan, Espo and Lanie – and Gates." O'Leary chokes. Petra starts, meeps, and runs out claws. O'Leary yelps.

"No claws, fluffball. 'Tain't nice," he reproves. Petra quirks her furry ears embarrassedly, and pulls the claws back. "An'?"

"And Gates was, um, supportive."

"Yeah?"

"Yep." Beckett doesn't mention why. Gates's childlessness is her business. "The others" –

"Took a bit of persuading," Castle says, with something of an edge. Beckett strokes down his spine, as she would if he were feline, and he eases.

"Anyway," she says briskly, "Gates made a suggestion."

"Order," Castle says sulkily. "As if we were idiots."

"She said we should hire out an indoor play centre."

"Sounds like a plan," O'Leary says, with the satisfied smile of a man who doesn't think it's got anything to do with him.

"Yep, and she said that Ryan, Espo" – O'Leary's smile starts leaking – "and you should all come along."

"Me? Why me?"

Beckett grins very mischievously. "She thought you could all do with the exercise." The grin drops away. "I can hardly get a bunch of kids round, can I? Even if they didn't care, their parents sure would. You guys all know now, and you won't be fazed by the switches. And, well, they like you."

"'Course they do. I'm very likeable," O'Leary drawls, and pets Petra so that she purrs babyishly. Unseen, Castle draws a line down Beckett's back into which she presses.

"I'll stroke you later," he whispers. She curves fractionally in pleased assent.

"So you'll come?" she says to O'Leary.

"Sure I will. Just remember that I don't fit in those tiny li'l tunnel thin's."

"'S okay. We'll send Ryan in. He's the smallest." O'Leary sniggers, and picks up Petra, who is apparently snoozing.

"She's asleep," he points out.

"It's her bedtime," Castle says, and heaves himself up to collect her. Beckett takes David. "Let's get their milk."

Milk having been administered to two very sleepy little humans, O'Leary consents to provide them with a hug before bedtime, and envelops them in his own huge paws. Since he's got them, he also gets the job of carrying them upstairs, and then it seems just unfair to deprive him of story-reading. Tonight it's classic Dr Seuss: _One Fish Two Fish_.

The children are tucked in, kissed goodnight, snuggle down together, and O'Leary is left to soothe them to sleep.

Castle takes instant advantage of the few minutes alone to pull Beckett firmly against him and kiss her in a very leisurely and possessive fashion. "That's better," he says, when he lifts off. "Mine."

"When O'Leary's gone, you can stalk me round the loft," she murmurs. "Sounds like you could do with some pleasant diversion."

"I'm always keen on pleasant diversions." He strokes up and down her spine, and she curves like her cat would and purrs into his ear. It contains no words whatsoever, and tells him lots about the later evening. Before he can respond appropriately, unfortunately, O'Leary's tread starts down the stairs, which Beckett feels is very poor timing.

"They're still cute," he says.

"You want them? You'd change your mind pretty fast after one of Petra's tantrums."

"Aw, she's just taking after her mommy."

"You… you… I do _not_ tantrum."

"You gotta admit you got one hell of a temper, butterfly." Beckett huffs sulkily. "You just use it better."

Castle doesn't say anything at all, but his eyes are crinkling wickedly. Beckett glares impartially at him and O'Leary. She does _not_ have a temper. She is merely… forceful. O'Leary is just being annoying. Well, she has a cure for that.

"Going back to the point, Bigfoot" – O'Leary grins massively at her: it's no insult – "I guess we're going to hire out a play area, and you, Espo and Ryan are all going to come and chase the terrible twins around it till they're exhausted."

"Them or me?"

"Both," Beckett snips, and sniggers at his face as he droops at her.

"I'd bring your vest," Castle emits wearily. "You'll need it."

O'Leary looks quizzically disbelieving. "You mean your cute li'l kitties ain't so cute?"

"They scratch." Castle winces in memory.

"I knew that."

"And Petra bites."

"Oh. That ain't so good."

"No. So bring your vest."

Beckett reflects that she had not told Ryan or Espo to bring their vests, and maliciously decides that they can do their own thinking. If they can't work out the dangers of two wildly excited children-kittens-cubs, they don't deserve their badges. They will, however, deserve the scratches. Though she will tell the twins off for it, just as she had earlier.

"Okay. An' if they try 'n' bite me, waaall, I guess I'm big enough to dangle 'em out the way till they learn better."

"Go right ahead," Castle says. Beckett nods. She'll take all the help they can get in socialising the tiny terrors.

O'Leary drains his beer. "Time for me to get home. Pete's cookin' somethin' good. Lemme know when you fix it up for." He exposes white teethbergs. "Can't wait to see Espo chasin' the furballs. That'll keep him fit."

Beckett sees him to the door. "Night," she says.

"Night, all," O'Leary answers, and trundles off, not shaking the floor more than a moderate amount.

The door closes behind him. Castle's expression alters from general friendliness to intent. Beckett smiles slowly and seductively at him, and is abruptly Onyx. As swiftly, he's the massive panther. Strength stalks sneakiness. Sneakiness winds up in the bedroom, still uncaptured, slithers under the bed, pauses a few seconds, re-emerges and flirts her tail and ears at strength and size. The panther coughs at her, she flicks her tail again, and curls up on the pillow. He bats gently at her, careful of her slim, smaller form, and she whips away again, winding up at the door.

About that point, she realises that while she wasn't looking, Castle managed to change, shut the door, and change back. That cheating _rat_! A large paw lands on her, and she huffs. Immediately, it's a large hand.

"Caught you," he says lazily, and fondles her ears. Of course he did. That was the whole point. And he's much happier, which was also the point. She sinks into his wonderful hands and the petting. He picks her up, drapes her over his chest, and balances her carefully while he loses most of his clothing. She purrs; he smiles sleepily, and when he puts her down on the bed she shifts back to Beckett to allow him to enjoy the fruits of his success. Of course, she'll enjoy them too. She pulls him down, and shortly there is nothing but them.

* * *

After chores and the general tidy-up after early-morning toddler wrangling are both complete, Beckett contemplates her phone and Ryan's number, which is staring at her meaningfully. She knows that she has to talk to Jenny. She just has the unhappy feeling that matters are careering out of their control. Beckett is not keen on matters being out of her control.

"What's up?" Castle asks, the twins being momentarily occupied.

"It's all getting too big," Beckett says miserably. "Something's going to leak or break and then we'll be all over the news. It might be easier just to make a public announcement."

Castle goggles at her, mouth open. " _You_ are thinking about publicity?" he squawks. " _You_?" He places a large palm over her forehead. "Nope, no temperature."

"I'm not ill. I'm not crazy. But it's just so _complicated_ already."

"Yeah," he agrees. Then he stops. "You know, there is one thing we could do."

"Huh?"

"Well, um, we can't take them to the playground when they might change and others would see them… but as we found out the other day, they're quite lively at night… and cats are nocturnal… and I wouldn't mind if they woke up a bit later…"

"What you mean is, we could take them to a playground much later in the evening than small kids would be out."

"Yes."

Beckett is flabbergasted. "That's brilliant, babe!"

Castle preens. "We could even try it tonight," he says hopefully.

"Yep. Definitely." She thinks. "Um, where? We need one that isn't locked up" –

"No, we don't."

"Uh?"

"Beckett, how do we get into Central Park?"

"Oh." She blushes. "Oh yes. We just sneak in as cats. All of us."

"All this telling people is getting to you. You're not normally this slow."

She growls at him. Castle wanders his fingers down her spine until the growl is gone, and smiles very smugly and happily.

"So we'll give the terrible twosome a longer nap after lunch, and then after dinner we'll take them out to the playground. Sevenish should do it: there won't be any small children around by then."

"It'll still be light, though."

"We can make it a bit later if you want. Let's try, at least."

"Okay." Beckett puts her phone down, without dialling, with a sigh of relief, just in time to be pounced upon by a feline mess of cub and kitten which eventually, once disentangled, proves to be kitten-David and cub-Petra fighting for the major share of her lap. She pets them both even-handedly and then plops them on Castle so that he gets a turn. He does most of the hard work, so it's only right that he gets a good share of the nice bits. He pets them both, and they purr and cuddle up. Beckett grabs her phone and snaps off a couple of photos for the very private album. That one is extra cute, and Castle's besottedly parental expression is quite adorable. He's such a sap. She loves it.

Both adorability and her happy mood are, of course, shattered when Petra decides that she isn't going to share Castle, Beckett fusses over David, who had been chased into her lap, Petra doesn't like that either, and the inevitable time out and howls result.

"Nope," Castle and Beckett say in unison. "You share."

Petra screeches even louder, and is shortly to be found screeching at an otherwise empty bedroom, in a playpen to stop her escaping. David says nothing, but looks very smugly cute. Beckett regards his little furry black head very suspiciously. She is not at all convinced that David hadn't provoked his sister, though since he appears to be able to provoke his sister simply by breathing ( _so_ like his father had once been to her) she may be being a tad unkind.

"I think running them round a playground for hours is an excellent plan," she says tiredly. "Minetta? Or Bleeker? They're both gated, and they're quite small with equipment, so they can't really escape and they'll stay interested."

"Play, mama?" David, converted into human, squeaks happily. "Wan' play."

"Sssh, sweetheart," Beckett hushes. "We're talking."

"Me talk."

"I know," Beckett sighs. He rarely _stops_ talking, or mewing, or purring, or growling, or some other form of noise. _Just_ like his father. "But not now." She turns back to Castle. "We'd better drive up. Just in case."

"Yeah. Walking might be healthy" –

"But experimental labs aren't."

"Yeah. Okay, let's go for it."

"While we're on the topic, there's Playgarden. Franklin and Church. I could call them about a private hire, I guess."

"Might as well."

Beckett stands up, dispossessing a none-too-impressed David from her lap, and goes to retrieve Petra, who has at least stopped screeching. This does _not_ mean that her mood has improved: merely that she has discovered a quieter way to make her immense displeasure manifest.

"Oh, h- _eavens_ ," Beckett wails as she enters the room, rapidly censoring her first words, which started at _oh hell_ and went downhill from there. Fortunately, she had shut the door, and equally fortunately, Petra was sulking and hadn't been prepared for her mother's arrival, since even in the tenth of a second shutting the door now takes (markedly faster than when they couldn't _move_ ), she is capable of escaping.

Petra, it appears, has discovered that cloth-and-net playpens are not proof against panther teeth and claws. It is – Beckett looks round, and revises that to _they are_ – shredded. She considers, in no particular order of desirability, screaming, shooting and sobbing. Or maybe all of them at once.

* * *

 _Thank you to all readers and reviewers, especially guests._


	9. Chapter 9

**Chapter 9**

"That was very naughty," Beckett says to Petra, in a frozen tone from which her daughter cowers. She picks up the cub and puts her in the cot. "Stay there." More cowering. The shredded remains of the playpens are collected up in absolute silence, and put outside the door. Petra turns into a toddler.

"Mama?" Petra falters.

"Be quiet. You are in big trouble."

Petra snivels. Beckett ignores it. Petra has massively overstepped the bounds of reasonable sulking and crossness, and now she and Castle will have to work out how to deal with her. No good ideas are occurring to her that won't punish David as well. Separating them is not the best plan, and David would be distraught if they weren't cuddled up in the same cot. (At some point, that will need to change. But not yet.)

"Daddy needs to know about this too."

"Not tell Dada."

"Yes. No secrets from Daddy."

"Not tell!" Petra howls. At which unfortunate moment Castle appears without David. He also appears to have summed up the situation.

"That pile used to be the playpens?"

"Yep."

Castle regards Petra as coolly as Beckett has. "That was very naughty," he says judicially. Petra whimpers. The combined weight of both her parents' disapproval and disappointment appears to be bringing home to her the magnitude of her misbehaviour. She converts herself to a kitten and tries to put her paws over her head.

"Change back," Castle says in tones of doom. Petra does. "Why did you destroy the playpen?"

She whimpers, without words. Castle waits. Beckett slides away to ensure David is not doing anything dreadful. They can't cope with any more dreadful deeds today. She slides back, reassured for the moment. Petra has switched back.

"Why, Petra?"

"Mama _naughty_. Not time out. Not fair."

"Mommy wasn't naughty. You were. Destroying the playpen was very naughty."

"Not," Petra sulks.

"Petra," Castle says with an intonation that brings her face up.

"No p'aypen. No _cage_."

They have never called it a cage: nor has anyone else where the twins can hear – they don't think. But they have taken the twins to the zoo.

"It's not a cage."

" _Is_. No cage."

Castle and Beckett exchange a glance. Petra, however naughty, does appear to have a logical reason for her actions, even if she was wrong.

"No-one will put you in a cage. But if you and David are fighting, you need to spend time apart." He stops. "So, if you and David fight, now you will be in one room and David in another. You won't even be able to see each other."

Petra's little face falls into abject misery. She starts to cry. Neither parent takes any steps to comfort her.

"You will stay here for another time out."

That means three minutes.

"In that time, you are not to break anything."

They both leave. Petra is still sobbing, muffled by a stuffed bear. In a couple of minutes, one of them will come to get her and all will be forgiven.

Downstairs, David is happily batting at blocks to see if they slide. They do. There is a small tidal wave of blocks against the bookshelves. David thinks this is fascinating, especially the cheerful clacking noise. Since he's happily occupied, they don't disturb him.

Three minutes later, Castle goes to get Petra. Since he dispensed justice, he dispenses forgiveness too. She's drooping and very miserable, and when put down converts herself into a kitten and merely curls up on a cushion: not interacting with anyone. It seems that she has really realised that she has behaved very badly. It is, of course, also possible that her misbehaviour has left her exhausted, which is more likely.

After lunch, which is punctuated by the repetition of _children get lunch, cats don't_ and _in your mouth, not your hair_ approximately one thousand times, the twins are tucked up for the remnants of their afternoon nap, and their frazzled parents take a rest. It does not involve a nap, euphemistic or actual. Mostly, it involves throwing the toys into the box and then collapsing on to the cleared cushions, snuggled up.

"That was not fun," Beckett says, stating the obvious.

"How'd she get the idea it was a cage?"

"Zoo, I guess. Ugh."

Gloom descends.

"We really need to find a way to teach them not to change."

"I know. Maybe if they're picking it up for eating we can use the same thing with seeing small friends?"

"They don't have any."

"They do. You took them to play with other kids up till last week."

"I guess," Castle says doubtfully. "You couldn't really call it playing. More organised mayhem in ball pools."

"Yes, but they enjoyed it. So maybe if we start just with Sarah Grace and do the repetition bit – children play, cats don't" – Castle groans at the thought – "we can start to make it stick."

"Yeah. You'd better call Ryan, then."

It's Beckett's turn to groan.

"But before you do…" Castle turns her firmly into him and kisses her.

"Mmm. What was that for?"

"We needed it."

"We _need_ a babysitter. For a week, and we could go up to the cabin and play chase for a week without traumatising the children."

"I don't think anyone else would put up with the terrorists for a week."

Beckett droops. Castle droops with her. The thought of a child-free week playing chase with Castle in the woods around the cabin is a wonderful – dream. And a dream is all it's going to be for another couple of years. That's parenthood. Or at least, that's parenthood of two terrorist twin shapeshifters. She kisses Castle, since at least they've got some time for that, in a rather _I-wish-we-had-time-for-more_ way which he definitely appreciates, and then unenthusiastically dials Ryan's number and puts the phone on speaker.

"Beckett? We got a body?"

"Not unless you count mine," she says gloomily.

"What d'you want, then? Not like you to be calling and it's not a dead body."

"You know we spoke about Sarah Grace coming to play?"

"Yeah?" Ryan says slowly.

"Well, we thought that if we hired out an indoor play centre, maybe you and Jenny and Sarah Grace could all come and we can start working on teaching the twins to stay human."

Ryan, presumably from the vantage point of an extra year of small child wrangling, snorts. "Good luck. We're still working on _hold my hand when we cross the street_."

"I didn't say it would be _easy_." Another snort. "Look, can you soften Jenny up a bit and then we can tell her about it as soon as we know when we can hire the play centre?"

"How do you think I'm going to do that? There's no way to soften this up!"

"Oh."

Castle weighs in. "Why don't the three of you come round now. By the time you get here the twins' nap will nearly be over and we'll have time to explain and then Sarah Grace can play with them here."

"Or we can run away," Ryan says dryly. "Okay. See you later."

Beckett swipes off and flumps on to the cushion and Castle, who _oofs_ , and then wraps arms round her so that she doesn't wriggle away. "Got you," he says. "Just stay here." Beckett is perfectly happy to stay here. She wiggles to become comfortable, and pillows her head on Castle's lovely broad chest.

"Cages?" she says after a time.

"I don't know where she got it either."

"I see her point, but now they'll have to go in separate rooms for time out."

"Or we buy two crates, like you get for really big dogs."

"That really is a cage. Can you imagine trying to put them into anything like that?"

"No, not for real. It's just a nice thought after this morning." He shifts Beckett so that her elbows aren't in his stomach. "Maybe we should get the crate for us. Protection." She sniggers. Castle kisses the top of her head. "Ryan'll be here soon. We ought to sit up, at least."

Beckett scowls. "I'm comfy," she points out.

"I'd rather be having a… nap," Castle points out in return. "But that's not on offer and anyway falling asleep in the middle is totally unflattering."

"Are you saying I look tired?" Beckett grumbles.

"No, I'm saying we _are_ tired." He stretches, and then sits up, tipping her to the side and then pulling her up too. "Maybe we should go to bed a little earlier."

"Maybe we should go to _sleep_ a little earlier," Beckett notes, and smiles seductively.

Castle's answering smile is lazily rakish. "Where's the fun in that?"

Not long later, the door sounds, and Ryan, Jenny and Sarah Grace arrive. At a year older than the twins, Sarah Grace isn't actually any bigger, but then Ryan and Jenny are relatively small. Beckett surreptitiously examines the little girl and hopes that her terrible twosome aren't too rough with her.

She looks at Ryan, who looks back at her unhelpfully blankly. That look, in the bullpen, says _don't ask me I haven't the first clue_. Time for some improvisation.

"Jenny," she says, "let's get some coffee and then I wanted to ask you a couple of things without the boys around." Castle chokes. Ryan blinks.

"Sure," Jenny says, with an exceedingly speculative look mostly directed at Beckett's flat stomach.

Shortly, they have ensconced themselves in the study, leaving the men with Sarah Grace and the likelihood of wakening twins.

"So what did you want to know?" Jenny asks. "Wondering about a good age gap?"

"No!" Beckett squawks, horrified. "Two is enough."

"Oh."

"Um… actually, something quite different," Beckett adds very hurriedly, before Jenny can suggest anything even more embarrassing, such as ideas to – er – spice up their life. She recalls that Jenny and Ryan had had a very – er – open relationship early on. Beckett and Castle's relationship is quite spicy enough. Suggestions are not required.

"Babysitting? Those twins are so cute."

"Um… about that. Cute, not babysitting. Um, there's something I need to tell you about them. Ryan knows already, but I wanted to tell you myself and that's why he didn't tell you."

"Mm?" Jenny says, with an interested look reminiscent of a falcon spotting a fat mouse.

"Um," Beckett gulps, "But you need to keep it absolutely secret. Just you and Ryan. You can't talk about it to anyone."

"Mm?" The falcon has spotted a whole tribe of fat mice.

"Um… we're shapeshifters. All four of us."

Jenny bursts into hysterical laughter. "How on earth did you pull that con off?" she snurkles. "Kev isn't that gullible usually. Did Rick do some amazing sound and light show with holograms?"

"Jenny…" Beckett says, "um… look here?" And she changes into Onyx.

Jenny uses a very large number of words that she surely wouldn't want Sarah Grace to learn. Beckett changes back.

"Not a hologram."

Jenny uses some more industrial language, which is amazingly incongruent with her demure appearance. Most of the non-profanity seems to be a long diatribe on the unfairness of Beckett looking fabulous as a freaking _cat_ as well as a woman.

"Um, do you wanna talk about this or just be left for a while? Because the twins are going to wake up soon."

"How have you kept this" – more bad language – "secret?"

"Adults can control it. The twins were synchronised with me, but now they're not. So it was fine for them to play with Sarah Grace when I could keep them human, but now you and Ryan need to know." She regards Jenny very seriously. "We _hope_ you'll still let her play, but they aren't very careful."

"How much damage can two" –

"Kittens. They're kittens. The human age seems to govern everything. But" –

"kittens do?" Jenny finishes.

"Um… that's the other bit."

"More?" Jenny says. So far, apart from the understandable amount of swearing, she's taken it better than any of Lanie, Espo or Ryan; or indeed anyone's family.

"Um… not just cats. Um… panthers?"

Jenny makes a gleeping sort of noise. More incongruous profanity arrives.

"Show you?" Beckett asks.

"It can't get any freaking weirder than it is – oh my God that is so freaking gorgeous!" Jenny seems set to dive on to panther Beckett and stroke her. So. Not. Happening. She changes back extremely quickly. "I mean, scary, but gorgeous. Wow. No wonder you're so badass." She pauses. "But Rick?"

"Him too. He whined till I changed him. But then the twins were born this way."

"Lucky you only had two," Jenny says with prosaic practicality. "Don't cats have litters? You could have had four."

"Ugh," Beckett emits with venom. "Two is plenty!"

"I'd like a second," Jenny notes.

"Up to you. Sarah Grace always seems pretty manageable."

"In public," comes back, with some considerable cynicism.

"We don't even manage that right now."

Jenny stops for a moment. "Guess not," she agrees. "Tricky."

"So anyway, we were hoping you'd let Sarah Grace play with them, here or Castle's going to hire out an indoor play for our private use" –

"Nice to be rich."

"Gates thought of it."

"Wow."

"And then we can start telling them children play but cats don't. Over and over and over again. I think I'm going to make a recording and just play it."

"Be kind, rewind?" Jenny snickers.

"Yeah." Beckett grins back.

"I'm game," she says confidently. "And if Sarah Grace says anything odd, well, we'll just laugh about her imagination. Don't all little kids love to play with imaginary friends?"

Beckett, most unusually, hugs her. "Thanks. When the terrorists wake up, we'll try it. Petra bites, though."

"Kids do. They mostly grow out of it."

"If they've got claws too?"

Jenny shrugs. She's surprisingly sanguine about the whole thing.

"How are you so calm?"

"I don't fret about what I can't change. You exist. I can't change that. And, well, you're both good people, so I don't guess that changes just because you're big cats." She smiles very mischievously. "I don't envy you the tantrums, though."

"Castle is all bites and scratches right now. Petra spends more time in time out than time _in_."

"Yep. Been there. Still there. Want a t-shirt?"

"No thanks. But if you've got full-body Kevlar, I'll have that. They don't issue us that at the precinct. Only vests."

Jenny snickers, and the two women emerge quite in charity with each other, all _ums_ and hesitations left firmly behind. Castle pouts, since he wants to know what went on. Ryan seems quite happy to remain in blissful ignorance.

"No terrorists?"

"Nope. Not a squeak – oh."

Squeaking is occurring.

"Better go get them."

"I don't think I need to," Castle says dryly, as squeaks, mews and scrabblings are heard at the stairgate, followed by the clatter of feline claws on the stairs. A double height stairgate appears to be an urgent requirement.

"Kitties!" Sarah Grace cries, and runs for them. She appears not to have noticed that said _kitties_ are actually rather larger than a normal domestic adult cat (though not quite larger than Castle's Maine Coon). The cubs slither to a halt as she dashes up to them. "Pet the kitties!" She wraps them into the sort of strangulating hug only an enthusiastic three year old can manage, which, quite astonishingly, does not result in growls, claws and biting. In fact, they both lick her face. She makes a disgusted noise, and sloppily kisses them back. "Play with the kitties!" Before the twins are quite strangled (Beckett doesn't think _dammit_ , but after the morning she's had a little strangulation in the abstract doesn't seem _that_ bad) she lets go of them, dashes to the toybox, and starts to tug out toys. Beckett is exhausted just watching her.

The twins are not exhausted. They bound over to her and start to pounce on the toys. Sarah Grace laughs and claps and slides the toys around – right up till Petra decides to be human, and David swiftly follows.

"Mommy!" Sarah Grace yells. "Look, Mommy! Kitty is a girl!"

"I a _boy_ ," David says very indignantly. Petra looks smug.

"Can I be a kitty too?"

"No, honey," Ryan says.

"I _want_ to."

David, unhelpfully, becomes a small, cute kitten and bounces on to Sarah Grace's lap. Her rather ungentle patting means that he changes back, swiftly. She squawks. David is not small.

"They're kitties! I wanna be a kitty too!"

Beckett looks at the terrorist twins. "Only children get to play with Sarah Grace," she instructs. "No changing. No cats. Cats don't get to play. Cats sit with Mommy or Daddy and watch."

The twins regard her with baby disbelief.

"No cat?" Petra cheeps.

"No cat. Be a girl."

Petra looks sidelong at her. Beckett looks back, firmly.

"Yes, Mama."

"Good girl. David?"

"Yes," he agrees, pouting slightly.

"Good boy."

In the background, Sarah Grace is still demanding that her unfortunate parents let her be a cat. Beckett is (privately) happy that someone else's small child is as demanding as hers. It makes her feel so much better.

Petra and David toddle up to Sarah Grace and take her away.

"Play," they say in unison, and each take an arm. Perforce, she comes with them. Shortly, they are all comfortably stacking blocks and stuffing shapes into openings. All four adults relax.

For a few moments.

Then David gets bored with the blocks, though (for once) Petra and Sarah Grace are playing co-operatively – or at least not fighting. Co-operative might be pushing the definition – and after a mere millisecond's consideration, turns into a cub, and dabs at Sarah Grace. It's pretty clear he wants to play chase.

"David, come here," Castle says warningly. "Only children get to play."

Sarah Grace turns round, glares at David, and turns away back to the blocks. David dabs again, harder, ignoring his father entirely. Sometimes, very rarely, he is very like his mother.

"David," Castle says. "Come here." David doesn't. Castle stands up, picks him up, and removes him from the girls. David growls, and tries to scratch, which fails miserably since all four paws and their attendant claws are dangling helplessly. Castle had adjusted to baby-shapeshifting geometry exceedingly quickly. "No scratching. You stay with me. Time out, and then if you don't change to boy you don't get to play."

David growls much more loudly, which has no effect at all on Castle. Ryan regards the flexing claws with some interest and more worry. Jenny regards the cub with an expression of fond amusement mixed with some surprise.

"I thought it would be Kate who dispensed discipline?" she wonders.

"Both of us," Beckett says. "They argue like cheap lawyers."

"Or like you in Interrogation," Ryan says, which on reflection wasn't the smartest thing to say. Beckett shrivels him with a glare, and follows up with a baring of teeth that effectively reminds him of her panther.

By the end of the afternoon, Sarah Grace is unscratched and unbitten, which is a miracle of Biblical proportions. Petra and David have been variously detached for turning into felines, but they've been relatively good about changing back again.

All in all, it's been a successful experiment.

* * *

 _Thank you to all readers and reviewers._

 _Alerts are a little messy at the moment, so I'll reply when I can! PM alerts are especially flaky._

 _The Caskett Cats are taking a Christmas vacation, in which I shall post my Christmas story, Choreographing Christmas, starting on Tuesday. As I'm travelling (again) the timings may be a little odd, but I hope to see all of you there. The Cats will return in New Year to finish the tale (or should that be "tail"?)._

 _NYAZ - the man who bit her was never seen again..._


	10. Chapter 10

**Chapter 10**

When the Ryans have gone, Beckett and Castle survey the mess with less distress than usual.

"Okay," Castle says, "let's all tidy up. Petra, you play slide the blocks to Daddy." She meeps happily and toddles off to start. "David, you play catch the blocks before I can and throw them in the box." He squeaks, equally happily. This is the only time that throwing blocks is allowed.

"I'll clear up the coffee cups," Beckett says, and does.

Castle does a bit of cushion straightening and bean bag retrieval, while putting other toys back in the box. Remarkably quickly, there is order.

"Petra, David," Castle says with an intonation and smile which they already know means that there will be a delightful surprise (which might range from a little ice cream to a trip out to somewhere interesting), "come here." They scamper up and dispose themselves on his knee, one knee each. Castle cuddles them in. Beckett looks on fondly. "After dinner, we're going on an adventure."

"'Venture?"

"Yes, an adventure. We're going to go out in the car, and go to a special place." He regards them very seriously. "Now, you have to do exactly what Mommy and I say, or we can't go again."

Two sets of wide eyes look impressed by his tone. "Yes, Dada," they both say. They sound as if they really do mean it. Time will tell if this is accurate.

"Dinner time first," Beckett says, rapidly assembling a nutritionally balanced meal with a presentation which wholly conceals the presence of all sorts of healthy vegetables. Whatever works. Dinner, as had lunch, involves constant repetition of the two mantras: _children eat, cats don't_ and _in your mouth_. However, no doubt out of sheer self-interest at the treat to come, the twins are relatively receptive. Or possibly they are hungrier than usual.

Twins mopped up and relatively presentable in tough clothes and little sneakers, instructions are issued.

"Okay. We're going to the car. Petra, you hold my hand. David, you hold Daddy's. You hold our hands until we say let go."

Both twins nod.

"If you let go, we don't go out, we go straight back home and you go to bed," Beckett adds in a completely _this is not negotiable_ voice. They nod again, much more sincerely.

Astonishingly, the car and insertion into child seats is achieved without a single protest or difficulty, although the volume of enthusiasm is ear-shattering until Beckett says, " _Quiet_ ," in her best threatening-suspects tone and even Castle automatically shuts up.

He drives. It's his car. Beckett grumbles under her breath. Castle cheerfully ignores her, as she had him every time it was her car, especially as she had never let him play with the lights and sirens.

They park as close as humanly (or felinely) possible to the playground, and Castle switches off the engine. The twins start to babble demands to get out.

"Shush. Listen to Mommy," Beckett says. "You do exactly what we say, or you go home. If one of you disobeys, _both_ of you go home. No do-overs. Straight home, first time."

The twins look at each other, horrified, and babble in their own private language. Petra sounds very like she's issuing orders. Beckett hopes they work better on David than _stay in the car_ ever did on Castle.

"We be good," Petra says, and pokes David.

"Yes, Mama."

"Good. Okay, listen up." Two sets of ears prick up, two pairs of bright little eyes regard her. "When I tell you, you change to kittens. Okay?"

"Yes."

"Mommy and Daddy will change to cats. Then you come with us."

"Yes."

"Okay. Now, we'll get out of the car. Stay children till I tell you."

Amazingly, both children do precisely what they are told. It appears that, rather serendipitously, Beckett has stumbled on a threat that works – spoiling the _other_ twin's fun. Collective punishment might be unfair, but it certainly seems like it might be effective. Once again, whatever works is what they will do.

The four of them wander casually up to the gates of the park. Luckily, no-one is around, and Beckett had made sure that they are not going to be in an area covered by street cameras.

"Castle, you change first." He does. The Maine Coon stretches alongside the railings. "Now Petra and David." They do. "Follow Daddy," Beckett says, and becomes her elegant Siamese. The four of them slip through the railings as cats. Castle and Beckett stop, and the kittens stare around in awe.

Beckett switches back for a moment. "You can play as cats or panthers," she says briskly. "Not children today. If you're good, we'll come back. If not, we won't." She is abruptly Siamese again. The kittens tumble around, trying to look at everything at once. Castle pads up to one of the frames, jumps, and slithers down the slide in a bundle of fur, legs and tail. Beckett makes herself comfortable where she can watch, and waits. The kittens race around the equipment, mewing happily. Castle prowls alongside wherever they are, ready if needed but otherwise letting them be.

As the twilight gathers, the park becomes sufficiently gloomy that no-one is around to notice. The streets are quiet. Beckett shifts back to human.

"Petra, David, five more minutes." Castle looks at her reproachfully. He wants to play for longer, but Beckett does not want to push their luck. It's all gone surprisingly well, and quitting while they're ahead is a good plan. She beckons Castle over, and when he arrives on silent feline feet, fondles his ears. His tail tickles over her. Right. That's him on board with going home.

"Time to go home," she says. "Stay cats, till I tell you." Castle leads off, the kittens follow, and Beckett slides back into cat form until everyone is safely out of the park and back almost to the car. She changes. "Everyone back to human," she requests, and shortly there are two tired children. She picks up one, Castle the other, and they are inserted into their child seats. They make it home just before they fall asleep. Hands and faces are wiped, the twins are put in their onesies and into the cot, and Castle is only four words into Scattercat when their eyes are closed.

"That worked really well," Beckett says when he comes quietly downstairs. "Great idea. Now all we need to do is find one which is away from any roads so that they can change as they please without anyone tattling to the papers."

"I'm full of great ideas," he smirks smugly. Beckett sticks her tongue out at him. "You'd tell the twins off if they did that."

"I've got a better idea than you," Beckett diverts. Castle wriggles his eyebrows. "You be panther, I'll be Onyx."

"I've got an even better idea than that. You be Onyx, and I'll brush you."

Beckett is instantly Onyx. Brushing is _still_ the best foreplay _ever_. She leaps on to Castle's shoulder; he carries her to the couch and then brushes her until she's a lax sprawl of darkness. Then he carries her through to the bedroom, places her gently on the bed, and she changes back.

They don't get to sleep any earlier tonight than they have done any other night, despite going to bed rather earlier.

* * *

"I need a plan for Gates," Beckett grumps dismally over breakfast.

"'Ates come," Petra says, unhelpfully.

"Don't talk with your mouth full." Another million times a meal repetition.

"Captain Gates is not coming."

"Wan' 'Ates to play."

"Not today." _Not ever_. She can see Castle thinking the same thing. Petra glares, humphs, and subsides into a sulk. This is not news.

"I play," David points out. Petra huffs. David huffs back. Petra glares, David scowls. They bear a remarkable resemblance to their parents at moments of disagreement. Neither parent points this out.

"Eat your breakfast, or ask to leave the table."

"P'ease down," Petra says.

"Me too." Castle raises his eyebrows at David. "P'ease."

Both children are removed and put down.

Some hours of continually interrupted thought later, Beckett has caffeine overload and a headache, but not much of a plan. She glares at her paper, but it doesn't magically improve.

"Fixed?" Castle asks.

She jumps. "No."

"Stop messing with it and come and relax. Be Onyx, or if you want be the panther. We could both be panthers," he adds hopefully, and looks pathetically boyishly at her.

Panthers sounds good. "Okay." She pads out, ebony and lethal, arranges herself on a cushion and observes the chaos about her. The twins notice her.

"Mama big cat!" David shrieks.

"Inside voice," Castle corrects. "Mommy _is a_ big cat."

"Pa'th'r," Petra attempts.

"Panther," Castle corrects, again. He does a lot of linguistic correction. "Say it again?"

"Panth'r."

"Good. Mommy's being a panther."

"Me panther" – pronounced correctly – "too." Petra pads over to her mother, and tucks herself tidily up next to her. Castle swiftly takes a photo. The matching outfits can be used to tease Beckett for some time, even if they are their skins.

" _I'm a_ panther too."

Beckett-panther rolls her eyes. Petra-panther notices, and tries it too.

"Two of you?" Castle wails pathetically. David toddles over to cuddle him. "We need to stick together, Davy-boy. We're outnumbered."

David looks confused. "Two of them is definitely more than two of us," Castle explains. He receives another dual eye-roll.

"Two!" David squeaks happily, and points. "One, two!"

"Good boy." Castle ruffles his hair.

Beckett tucks her head tidily on to her paws and relaxes, as much as she ever does around the twins when they are awake. As a panther, her head doesn't hurt nearly as much. Petra pats at her, remarkably gently, and meows. Beckett gently pats her in return, and tickles her with her tail. Petra likes that, and tries to do the same.

It's unusual for her to try to copy either parent: normally Petra is independent to the point of insanity, though she very rarely takes life-threatening risks, or makes the same mistake twice. In any event, signs of civilised and gentle behaviour should be encouraged. There haven't been many, and while intimidation works for Beckett, she can (occasionally) do empathy and gentleness too. If she must. Petra is still stuck firmly on the intimidatory side of the dial, with no inclination to gentleness. Beckett therefore plays tail-tickling rather longer than she would normally wish to.

The remains of the afternoon pass in soft panther-play with the two mischievously pouncing cubs, who are thereby sufficiently tired out to be bathed and put to bed without too much complaint.

"What's your plan?"

Beckett makes a horrible face at Castle. "Underdeveloped," she says bitterly. "Why does Gates have to see a _plan_?"

"So we get the twins to age five without them being taken away by mad scientists from Area 52," he replies, with less humour than normal.

She droops. "I know. But I don't have much." She stares at the floor. "I got nothing, really. Just keep taking them to playgrounds and hammer home the message about staying in the same form."

There is a pause.

"I just can't get past the idea that Gates squashes any reports and 'loses' any difficult footage."

"It's a start. What if we told her which playgrounds we were planning to use, and she helped us…um…keep any street cams switched off?"

"Can she do that?"

"I don't know."

Both of them droop. Fortunately, they droop into each other.

"Change, Beckett. I'll pet you. Then you can pet me."

"I've got a better idea. Let's go and pet each other, without any changing."

Castle's eyes darken. Beckett's spark with gold.

"Sounds just perfect," he says, and pulls her to standing, where he kisses her deeply. They reach the bedroom with some haste and, rapidly, far fewer clothes. Shortly there are no clothes at all, except on the floor. A while after that, there is an aura of contentment over their sleeping forms, snuggled together as close as can be. Beckett wakes briefly in the night, takes a moment, then turns into Onyx and snuggles into Castle's neck, right where she always has, even before he knew about her.

* * *

"Detective Beckett," Gates says ominously, mid-afternoon on Monday. Beckett obeys her imperious gesture to follow her into Gates's office, and shuts the door.

"Your plan, if you please."

Beckett winces.

"Surely you have a plan?"

More winces.

"Explain." It's sharply frigid.

"I got nothing," Beckett admits. "There's _no_ plan that can deal with this. All we can do is take them to playgrounds when most kids have gone home, and keep telling them that they have to be human not cats." Her mouth twists. "Toddlers are disobedient enough when they're human. Ours have a whole new level of causing trouble. All it would take is one change when they're cross or mischievous or just forget and we'll all be in a lab somewhere."

Gates regards her coldly. "And yet they exist. Are you planning to confine them for the rest of their lives?"

"No! I'm trying to make sure they're _not_ kept prisoner. But right now we can't put them in daycare and we can't take them to playgrounds without serious planning. We don't have so many people we can trust that have _children_ , and anyway even good friends sometimes… aren't."

"Mm. I must admit that I did not expect you to have a plan. I, too, see no easy way to handle your situation."

Beckett boggles at Gates. "Sit down, Detective. Let's think about this together. I do not want to see your excellent work record destroyed, nor do I wish you to have to resign to manage the position. There will be a way to deal with this." Gates's cool eyes blink slowly. "We merely have to find it."

Beckett practically falls into the hard chair behind her.

"Now, describe to me again what you have already done."

"We've told Lanie – Dr Parrish, and Esposito and Ryan." Gates nods, judicially. "Castle is booking out the indoor play centre, now we know it has no camera coverage, and everyone will come. Ryan's daughter came to play on Saturday, and it went okay."

"Mm." Gates ponders for a moment. "Detective, I understand that Mr Castle donates quite heavily to charity."

Beckett stares at her. "How do you know that? He never talks about it. They're not _allowed_ to talk about it."

"I have my sources. Just as you have yours." Gates glares, coldly. "That is not the point. My point is that you might find it rewarding to take a, shall we say, more directly _involved_ attitude to certain forms of charitable donation."

Beckett regards Gates with complete incomprehension. Gates sighs. "Perhaps you should increase your caffeine consumption, Detective."

"Yes, sir. Would you like one too?"

"So you _can_ pick up a hint. Yes, I would. While you are making them, you might consider the nature of children's charities."

Beckett goes to make coffee for both of them. Hers is considerably stronger than usual or indeed healthy. Halfway back to Gates's office, it finally dawns on her what Gates had meant. She rushes in, deposits the coffees and shuts the door.

"You're suggesting we should take the twins to children's homes to play with the toddlers there. And if we gave a false identity" – Gates smiles, coldly – "you'd back it up with a reference." Beckett stares at Gates's almost-approving face. "And you know some of these places," she says, "don't you? You volunteer. Or something." She stops. Gates's expression is locked down hard.

"There is no need for you to demonstrate that you have learned some unappealing traits from Mr Castle. You do not have to express any further thoughts of that nature. Discretion is a virtue."

"Sorry, sir."

"You may make amends by arranging a further evening at your home." Beckett's jaw drops. "As I have said" – the tone implies that she shouldn't have to say it again – "I like cats. I also like your twins." Beckett hears _and I can put up with Mr Castle if I absolutely must_.

"Yes sir." There really isn't anything else to say.

"I will provide you with some appropriate places to contact. I suggest" – Gates looks down her nose at Beckett in a way suggesting that Beckett is less than fully intelligent – "that you use different identities at each, and spread your visits widely. _Very_ widely. Unless you wish the charities to discuss the occasions."

"No. Absolutely not," Beckett agrees, very quickly. "Yes sir. Thank you, sir."

She leaves extremely hurriedly, and thus misses Gates's amused glance at her.

* * *

"Castle! Babe, I'm home," she calls as she rushes through the door. She is greeted by a twin hurricane screeching "Mama" at full stereo volume, and drops to her knees just in time to withstand the landfall.

"Hey," Castle rumbles happily, and plops down to hug her and the twins. "Just in time for dinner. Their dinner."

Beckett smiles, a little weakly. "Yeah, um, about that…"

"You caught a case and you've got to go to Philadelphia?"

"No, no. We can have dinner just as usual."

"Dinner!" squeaks David. "Dada, dinner!"

"Dinner!" Petra adds. It sounds more like an order than a request. Beckett turns her round to meet her eyes and raises a brow. "P'ease."

"That's right. Please."

"What dinner?" David wants to know.

"Chicken."

"Yum."

Chicken, or indeed any form of meat, is always popular with their carnivorous twins. When they're bigger, and can be safely taken to restaurants which do not cater exclusively for families with small children, they will undoubtedly enjoy such delights as rare steaks. Beckett merely hopes that they will remember to enjoy them with _human_ teeth.

"Come on then. Let's fix you dinner."

Castle scoops up both twins, one in each arm, and conveys them to the kitchen. Beckett efficiently assembles dinner and puts it out, watched with interest by both twins and mischievous admiration by Castle.

"Why Dada not cook?"

"Mommy can cook too," Castle says.

There is a thoughtful silence. Then, "Dada cook. Mama work."

"Daddy works too," Beckett says into the stunned silence. "Daddy writes books."

It's instantly clear that this has passed their pair by. "Dada _work_?" Petra asks, in her best imitation of Beckett's disbelieving tones as used on lying suspects.

"Yep," Beckett says matter-of-factly. "Daddy works. That's why you're not allowed in his office."

The twins regard each other, and then Castle, who hasn't yet managed to find words.

"Book?" Petra queries.

"Books. Grown up books."

That was a mistake.

"Dada write _me_ a book," Petra says firmly. Castle opens his mouth. Beckett glares fiercely at him, and he shuts it again. Their twins do _not_ need to know that Castle wrote books about her. Especially not p105. They'll likely need enough therapy as they're growing up. She goes for distraction.

"Dinner's ready."

The twins start to clamour. Beckett puts their bowls and spoons down, and takes Petra to be strapped into her high chair as Castle deals with David.

Dinner, surprisingly, passes off with a much lower quotient of _in your mouth not your hair_ and/or _children eat, cats don't_ than a few days earlier. Beckett meets Castle's eyes and their thoughts align around _how long will this last_?

"Playtime, then bath time," Castle says happily to the well-fed and wiped up twins, as they scamper round the floor. Petra turns herself back into a toddler, and wanders over to sit on his knee, favouring him with a doe-eyed look of which Beckett is instantly suspicious.

"Book," she says.

"What do you say?"

"P'ease book."

"Sure, honey. Which book? Zachary Quack? Very Bad Day?"

Petra shakes her head. " _My_ book."

"Go get it, then."

"Dada write it."

Oh, God. Petra has developed memory which lasts longer than a mayfly's. That's all they need.

"I'll tell you a story," Castle says, slightly wide-eyed and flustered. "That's the same as a book."

Petra looks dubiously at him, which sits oddly on her toddler face, and then capitulates. "Kitty story," she says hopefully, and snuggles into her father as he begins. Beckett leaves them to it and plays block building and tower demolition with David until bath time.

* * *

 _Thank you to all readers and reviewers._

 _Happy New Year to one and all, and I hope you had a great holiday season._


	11. Chapter 11

**Chapter 11**

"So what's up?" Castle asks once the twins are safely stowed in their cot.

"Gates."

Castle acquires a very sympathetic expression. "What went wrong? Did you breathe the wrong way?"

"Worse."

"Worse? What happened? She didn't fire you?"

"No. Worse than that."

Castle stares. "What _happened_?"

"Gates hauled me in to discuss the plan I don't have. Then she told me off and then produced her own plan" – he gapes – "and then announced that she was visiting us again." She pouts. "She likes the twins."

"She had a _plan_?" Castle emits faintly, his face suddenly pallid. "She wants to visit _again_?"

"Yep." Beckett pulls a face. "It's a good plan, too," she says crossly. Castle's eyebrows fly up. "She suggested – well, it sounded more like an order to me – that we took the twins to some children's homes to play with the children there. She'd fix it so that we could use fake identities and she'd vouch for us."

Castle hums thoughtfully.

"But then I said I guessed she'd got some interest in them and she pokered up like a shot and then I apologised and she used that to inveigle an invitation."

"Interest? Oh. Oh yes. She doesn't have children… Oh. That maybe wasn't the smartest thing to say. You're getting like me," he says happily. Beckett purses her lips, disapprovingly. "I guess she can't have children, so she's supporting some children's charities. I'd never have guessed." He stops. "Anyway – she wants to _visit_? Again? What did we do to deserve that? I've been good."

Beckett snickers. "You're very good, babe. Very good at being very bad. What you did last night was very bad indeed."

Castle smirks. "You enjoyed every minute of it." The smirk turns to a lazy, sensual smile. "If we tidied up, I could be very, very bad some more. Then you could be very naughty too." Beckett smiles equally seductively, and the family room and kitchen are cleared in double quick time. Castle shivers once, becomes the huge panther, coughs – and pounces, pinning still-human Beckett to the couch. She laughs, fondles his ears till the purr rumbles through his chest and his head is lax in her lap, and then switches to Onyx, swats his rump and skitters to their bedroom, where she's already stretched across the bed when he chases after her. He leaps up, butts his head into her hands as she plays with his ears, and then is suddenly as human as she. Strangely, Beckett purrs just as much when human as when Onyx, when he's stroking her. Equally strangely, he growls as much when she's stroking him.

Later, they're snuggled up together, almost asleep, happily content and satisfied with each other.

"So tomorrow, will Gates tell you these children's homes?"

"Guess so. When are we hiring out the indoor play centre?"

"Saturday late afternoon. Will you tell the others?"

"Sure," he yawns. "You tell them too." He turns over, and cuddles her in. "Night, love."

"Love you too," she emits sleepily, and then there's only quiet and soft breathing.

* * *

"Why did you agree to this?" Castle grumbles.

"Like you could have said no to Gates either."

"'Ates?" Petra squeaks, delighted. " _My_ 'Ates."

Her parents regard her with horror.

"Not your Captain Gates," Castle chides. "Now say it properly."

"'Apt G-ates. C-apt Gates!" she manages triumphantly.

"You and David have to play nicely and share Captain Gates," Beckett warns. "Otherwise time out." Petra growls at her, despite being in child form. "No growling." David bounds up, happily panther cub, and pounces at Beckett. "No pouncing with claws," she points out, staring very hard at the sharp points, which have only missed her dress pants because her own reactions are lethally fast. David miawrrs at her, which is very cute but doesn't address the issue. "Change to child, please." He does. He knows that tone.

Beckett picks him up and holds his limpid gaze. "No claws. Claws means time out."

"'Es, Mama."

A moment later he's happily scampering around the floor, chased by Petra, both of them babbling in something that might, with considerable translation and correction, become English. In a year. Or three. Or ten.

"They'll develop proper language pretty fast, now," Castle says reassuringly. "Just look at Sarah Grace. We just need to keep talking to them and correcting them."

"I'll be a lot happier when they say Mommy not Mama. I feel like I'm in Little Women."

"That was Marmee," Castle points out unhelpfully.

"Shut up."

"Bad Mama," Petra says. "Naughty."

"That was rude, Petra," Castle says firmly. "You don't tell Mommy off. Not appropriate."

"So'y," Petra mumbles. It doesn't sound sorry at all: however, she's said it.

Beckett regards the wine bottle with longing, and it's not even six o'clock. This is not uncommon in dealing with her terrorist twins. Parenthood requires its edges softened, though frequently the softening is (not that she'd admit it to anyone other than Castle) her snuggly infants bouncing up to her and squeaking _Mama_. Today, however, involves Gates, and therefore something stronger is needed. Soon.

Hard upon that thought, the door sounds and Gates is among them, spreading dread and terror. Of course, not to the twins. Petra scrambles over to her, not accidentally pushing David out of the way in the process, and raises her arms to be picked up. Astonishingly, Gates obliges.

"Hello, Petra," she says to the happy little face. "Why did you push your brother?" The happy little face pouts, and becomes cross.

"My" – pause for effort – "G-ates."

Gates raises a quelling eyebrow, to Beckett's deep appreciation. "You can't own people," she says coolly, and puts her down to greet David in the same way. David bats eyelashes at her, and receives a chilly smile. Petra's face indicates an incipient tantrum, until she catches Gates's inquiring stare and thinks better of it.

The evening progresses very much in the way of the previous time, with the added curiosity of the impeccable and stern Gates sitting on the floor playing blocks and pull-along noisy toys with the children, after which she participates in bath time (though not teeth-cleaning) and reads them their story.

"Wine?" Castle asks when she returns, having (Beckett is sure) terrified the twins into slumber.

"Thank you." Gates takes the wine, and sits down. "Did you consider the list of children's homes?"

"Yes," Beckett replies. "We did. We've come up with a sensible order."

"As far away from Manhattan as possible," Castle says heavily. "And only for an hour or so at a time."

"Why?"

"Because that's about the limit of keeping the twins human," Beckett states flatly. "We're not taking any chances here. It's risky enough as it is."

"But they have to have interactions with other children."

"That's the _only_ reason we're going along with it. They have to be able to play with others."

"I still don't like any of this," Beckett growls, the panther bleeding through her voice. "There are too many things that can go wrong, and too many cameras."

"I can reassure you about that. Cameras are not permitted in the children's homes. Some of them are being protected from abusive parents, and any photos can be misused. So we don't allow it."

Castle exchanges an interested glance with Beckett. "We" don't allow it sounds very much like Gates is heavily involved. Given it's Gates, she's probably in charge, much like Ghengis Khan was in charge of the Mongol hordes.

"Thanks. That's helpful."

"And I shall be there." Castle gleeps under his breath. "That should ensure no… difficulties. My powers of observation have not diminished. If I see nothing, there's nothing to see."

"Thank you," Beckett manages.

"What is the planned schedule?"

Talk turns to the schedule until Gates takes her majestic leave, after which Beckett and Castle finish the wine in very short order and retire to their own rest. Gates is very tiring, and her helpfulness is delivered with sufficient sardonic regard that it riles them both.

* * *

"Petra, David," Beckett calls. "Time to tidy up."

"No!" David says.

Petra regards her parents carefully. "Why?" This is a newish word, which is rapidly becoming more common. Beckett can suddenly see the future and it involves interrogation. Of her.

"You'll find out when it's tidy."

This apparently satisfies Petra, who babbles firmly at David, who pouts at her, looking startlingly like his father. _Unlike_ his father, he starts to do what he has evidently been told to. The pair of them help to tidy up, and then look expectantly at the adults.

"We're going to a play centre," Beckett says.

Castle grins at the twins. "Uncles Ryan, Esposito and O'Leary are coming to play too. And Sarah Grace."

Much happy shrieking results from this pronouncement. _Most_ of it emanates from the twins.

Half an hour later they're at the play centre. Before they leave the car, Beckett reiterates the rules.

"You have to stay children until I tell you you can change. Any disobedience, and you _both_ go home. No do-overs."

"Yes, Mama," say two little voices. They sound about as cowed as they ever are, that is to say, very little.

"And no biting or scratching," Castle adds very seriously. "That will mean going home too."

"Yes, Dada."

"Let's go."

The twins have been to indoor play centres before, but only very small ones. This one is enormous in comparison. Even Beckett is impressed. Castle's eyes sparkle. They've got there first, as planned: Castle deals with the desk staff and Beckett ensures that David's small sneakers are removed and neatly placed in the shoe bag. Petra is intrigued.

"Why, Mama?"

"So they don't get lost."

"Why lost?"

"Look at the playground. If you took shoes in, they'd get lost."

"Oh." Petra's brow furrows. Beckett spots the trap, and the next _why_.

"If you don't leave shoes here you are not allowed to play."

"No play?"

"No playing with shoes on." Petra plops her shoes in the general direction of the bag, which is good enough. "Now you can be cats."

"Where David?"

Oh, _shit_. Beckett looks frantically around.

"Mama! Look at _me_!"

Petra screeches horribly and takes off at pace after David, who is already high up in the play centre. She doesn't sound happy about being behind him in the fun stakes. This is not news.

Beckett finds herself a seat, considers for a second and then convinces a machine to accept enough coins to spit out something that might be considered coffee. Or caffeinated. Or merely hot liquid. Happy shrieking from within the play centre indicates that the twins like the new game. Beckett merely sips her drink and hopes that she can have five whole minutes of peace. It occurs to her that she hasn't had a nice, long, relaxing bath since the twins were quite tiny, preferring to spend their limited time alone with Castle.

"Hey," says the man himself. "Where are the twins?"

"In there somewhere."

A small furry face looks out from the very top.

"Ah. There." He looks just a little wistful.

"Go on. You know you want to."

Castle grins, and unties his shoelaces. "Back soon, babe," he tosses over his shoulder as he disappears into the enormous playframe, shifting as he goes. Shortly, the massive panther appears at the top. Beckett smiles fondly at her coffee. She'll go in later. Castle loves playing and is prepared to roughhouse with the cubs.

"Yo, Beckett," pierces her reverie.

"Butterfly, I found a pal or three."

"Hey," Ryan adds.

"Wanna play," Sarah Grace squeaks.

"Sure, honey," Jenny, bringing up the rear, agrees. "Shoes off."

"And you three," Beckett says. "Castle's already in there." Mischievously, she doesn't mention his form.

"Aw, but…"

"Nope. Playtime." She smirks. "Unless you can't keep up with three small children." Sarah Grace is already almost in.

"Course I can." Espo takes the bait. His boots are off in no time, revealing the small hole in his socks.

"Off you go, Kev," Jenny encourages.

O'Leary looks in vain for a shoe bag to put his size fifteens in. He doesn't find one, and sets them together on the floor. They look lonely. He ambles off to the playframe, and leans up.

"Lele!" Petra shouts. "Lele play!"

"Sure will, furball." He ambles inside, squeezing through the gap, and shortly his disconnected head appears. Petra-suddenly-kitten pounces on the buzz cut, and O'Leary squawks. "No claws, troublemaker." His reprimand is rudely interrupted by a full scale yell of terror. It seems that Espo has discovered Castle. _Beckett_ recognises the noise as a happily predatory growl, likely signifying nothing more than Castle's mischievous – probably – desire to annoy Espo. On the other hand, Castle had been pretty pissed with Espo the other week, and it's not inconceivable that Castle is taking a little well-justified revenge. He's still joking, but… there's an edge that hadn't been there before, as the growl comes again.

Suddenly, before she can worry, it becomes a lazy, deep purr. David must have appeared, since Petra is still amusing herself with O'Leary, who doesn't mind a bit. Sarah Grace is shrieking happily, and Ryan's light voice can be heard encouraging her to climb higher.

Beckett drains her coffee, and looks at the playframe. It's really rather inviting, and her panther could do with a stretch… but she doesn't want to leave Jenny on her own. That's rude.

"Off you go," Jenny says, catching the direction of her glance. "I brought a book, and I _never_ get any time on my own."

Beckett doesn't need told twice. Her shoes are neatly placed, but she's her panther in a second, flashing sleekly ebony past the entrance and in.

Not long later, Castle emerges, still a panther. He's forgotten that Jenny has never seen it, and pads up to the table where she's immersed in her book. She looks up, and shrieks louder than any of the children. Even as a huge panther, Castle looks embarrassed, shivers all over and becomes human.

"Sorry," he says. "Forgot you hadn't seen me."

Jenny recovers herself. "You're huge," she says. "Much bigger than Kate."

Castle grins. "Yeah. She's meaner, though. 'The female of the species is more deadly than the male'," he quotes happily.

"Does Beckett know you say that?" Espo asks from behind him.

"Yep, and she agrees. She's the one with the gun." He regards Espo. "Breathing a little hard there, _bro_." Castle is not breathing hard at all.

"Your twins move fast."

"Just like their parents."

"Stop it," Jenny says, with exactly the same commanding tone that Beckett might use. "You're both supposed to be adults, and I thought you were friends. Go play with the kids."

The two men slink off, muttering. Jenny smirks at their backs, and then catches a small fluffball as it bounces into her lap.

"Which one are you?"

The fluffball turns into David, who looks cutely at her. "Dav'd. Wan' cuddle. Where mama?" He turns back to a kitten, which Jenny strokes.

"Mommy's playing in the playframe."

David turns a sleepy blue eye on her, and then curls up in her lap. Clearly he isn't bothered by that. Jenny looks down at him and smiles. "Guess you're not shy." She goes back to her book, only too happy to have quiet time. Some moments later David bounds back into the excitingly new game. Shortly after that, there is the sound of childish squabbling, and shortly after that parental chiding.

A lot later Beckett emerges from the playframe, pink and tousled. "That was fun," she says. She flops into a chair, and as swiftly rises to drain the water fountain. Then she sinks back down. "Hopefully they'll all be as tired as me when they come out."

"I hope Kev isn't," Jenny smirks. "We don't get much time together." Beckett declines to enquire further. She really _so_ doesn't need to know.

Eventually the boys emerge. All four of the boys, plus a tired Sarah-Grace and two very tired little twins, human again. O'Leary has Petra, who is clinging to his t-shirt in a way strongly suggestive of ownership. Castle has David, who is snuggled up to his father in a way strongly suggestive of sleepiness. Neither of these attitudes are new news.

Everyone agrees that it had been a wonderful idea, and a great afternoon. To be repeated, as frequently as anyone wants, or Castle funds. It's Beckett who says on the way home, "I think we should only do that occasionally."

"Why?" three voices ask.

She winces. _Toddlers_ asking why is normal. Irritating, but normal. Castle, however, is _not_ allowed to ask _why_. Three of them all asking _why_ will drive her totally insane in an hour.

"Because we don't have treats every day," she says, aware from the moment it leaves her mouth that it's weak.

Castle pouts at her, but on receiving a meaningful glare doesn't say any more. Fortunately the noise of the engine is sending her tired terrorists to sleep, which reduces the _whys_ to a level where she won't need to explain _why_ she's hitting the wine bottle.

They achieve home, and shortly after that achieve bedtime for the children.

"Why not do that every week?" Castle asks. "We can, you know. The household budget wouldn't even notice."

"They can't just play with us, babe. You know that too."

"I guess. It was fun, though."

"I heard you growling at Espo."

Castle's ears turn pink. "Just a joke." Beckett raises a very sceptical eyebrow. "Okay. Mostly a joke. He was mean to us, though," he says, very small-boyishly.

"You still can't bite him."

"Not even a little bit?"

"Nope." She smiles, lazily. "But you could come chase me round the bedroom." Castle's eyes darken, and any hint of boyishness disappears in the surge of very adult masculinity. Two steps later, he's on her.

"Why chase, when I've already caught you?" and he sweeps her up and carries her to their bedroom.

* * *

"I still don't think this is a good idea," Beckett grumbles as they pack the twins into the car, two weeks later.

"You wouldn't let me pick the false name," Castle sulks. "That isn't fair."

"Nobody is going to believe that Carter, Callie, Cosmina and Cosmo Charteris are real names, Castle!"

"They were fine names," Castle mutters.

"We'll do much better with Rick and Kate Bannerson, and David and Petra their kids."

Castle mutters blackly all the way out on to the interstate, and all the way to the children's home, and only stops when Beckett points out that they won't be allowed in if he doesn't stop. The thought of something more to tire their terrorising twins out (and, not incidentally, allow them an uninterrupted and gloriously _adult_ evening) is too good to miss.

"What's _that_?" he squeaks, as they park. "You didn't tell me she was coming."

"I _forgot_ ," Beckett wails. So had Castle. She did _so_ tell him.

"Gates!" Petra shrieks happily.

" _Captain_ Gates," her parents say in exasperated unison.

" _My_ Gates," Petra contradicts.

"If you can't be polite, you don't get to play with her," Beckett says firmly. " _Captain_ Gates."

"Cap'n Gates," Petra mumbles, unconvincingly.

"Why we here?" David asks.

"New people to play with. But you need to stay children."

David pushes out his lower lip, which is adorable, but manipulative. Very much like his father, in fact.

"Not wanna," he grumps.

"Okay, Petra will play and Daddy will take you home. I'm sure Petra will stay a girl."

"I be girl," Petra says, annoyingly smugly. "I play nicely." David wails angrily.

"Nope," Beckett says briskly. "Be a boy, like Daddy, or go home. Petra and I will have a lovely train ride home."

David's face turns red and scrunches up. Beckett ignores him, extricates Petra and takes two steps away from the car.

"I see you subscribe to the _brisk_ method of parenting," Gates notes sardonically, over David's wails.

"I'm in charge," Beckett points out. "They are not." Gates appears to be thinking _just as well_. It matches Beckett's thoughts quite precisely. Behind them, Castle is dealing with David. A rumble of _Mommy said be a boy, or go home. Which is it?_ is audible.

"Wanna be _cat_!" David howls.

"Okay, home then." Castle checks David's safety harness, and then gets into the driver's seat.

"Not home!" arrives at earsplitting volume, followed by floods of toddler tears.

"Then what will you be?"

"Boy," David snuffles miserably.

"Okay."

Castle hoists him out and cuddles him up to a broad shoulder. "He's not normally like that," he says, catching them up. "Maybe he's tired." He pats his sniffling son, who has slung arms round his neck, soggily.

"Go play, Ma- mommy," Petra orders. "Come play," she says to Gates, who takes a small hand with impressive sangfroid and without, it appears, any suspicious stickiness transferring itself. Beckett, magically freed, saunters along behind her daughter, who is babbling to Gates in tones more suited to the Academy drill sergeants. Gates appears to find it amusing.

* * *

 _Thank you to all readers and reviewers._


	12. Chapter 12

**Chapter 12**

The children's home is quite small, and, for an institution, relatively warm and friendly. In a playroom decorated with comforting murals and with a number of chewable board and plastic books and plenty of tough toys, they find six children who appear to be aged between two and four. There are also three adults. Two are motherly types of comfortable dimensions and average looks. One is a tall, thin male of around thirty.

"Mr and Mrs Bannerman?" one of the motherly types says. "Thank you for coming. Mrs Gates has vouched for you. If you would just come this way to complete the forms…"

"Mama, who Miz Gates? _Capt'n_ Gates," Petra attempts to whisper. This being Petra, it's unfortunately clear.

"Shh. Both are right." Beckett doesn't look at Gates when she says that. "You say Captain Gates."

"Wan' play," Petra says, satisfied. For now.

Beckett looks at the motherly type waiting for her to follow. "Is that okay?"

"Yes."

"Okay. Petra, you can play. Be gentle." She picks her up and under the guise of hugging Petra, puts her mouth to Petra's ear. "Stay a girl, or we go straight home."

"Yes, Mama." She wriggles to be put down, and on her feet touching the floor runs off to investigate these interesting new people.

"I'll watch her," Gates says. This is only marginally reassuring. Petra is far too fond of Gates for Beckett's peace of mind. Of course it's lovely that Petra is developing relationships with other people – not least so that Beckett gets a break – but Gates is…um… _senior_ to Beckett. Beckett absolutely does not want Petra to realise that Gates is entitled to give Beckett orders and that Beckett has to obey them. Petra might try it. It won't work, but it's a fight Beckett could do with avoiding.

Castle is still patting David, who is not evincing any interest at all in being put down and playing with new people.

"You go," he says, just managing not to say _Beckett._ "I'll keep an eye on Petra and David."

Beckett follows the motherly type to a small, messy office where she completes, with truth but not exactly the whole truth, various disclaimers and warranties that her children are disease free and perfectly normal. For a wide definition of normal, to be sure.

"I'm sure I've met you before," the woman says. "I'm Ms Cotter. Do you remember?"

Beckett makes a pretence of thinking hard, and tries not to panic. There hasn't been much publicity, and she's always kept well away from the book parties, but… "I'm sorry, I don't remember," she says politely. "Maybe at a fundraiser?"

"Maybe that was it," Ms Cotter agrees, taken in by Beckett's breezy confidence. "Okay, that's it. Mrs Gates confirmed everything else. We're really grateful you'd bring in your twins. So many people just don't want to know about these poor kids."

"Happy to," Beckett says, thinking something akin to _if only you knew about our twins_. "I just hope they play nicely."

"Don't worry. Toddlers can – excuse me – be like little animals until their brains mature."

Beckett barely preserves a straight face. _If only you knew_ , she thinks again. _Just as well you don't_. _I don't think you'd appreciate the literalism._

"Shall we go back and find out?"

"Let's," Beckett agrees.

Back in the playroom Petra is enthusiastically bashing at a xylophone with another small child. They appear to be having fun. No-one else appears to think the resultant cacophony fun: a sentiment with which Beckett is in complete agreement. David, most unusually, is still cuddled up with Castle, and is, even more unusually, sucking his thumb. On closer examination, he's very sleepy and somewhat red eyed. Since he seems to be quiet, not obviously ill and not screaming; Beckett leaves them to it, and inspects the remainder of the room. Much to her astonishment, Gates is sitting on the floor reading a rather chewed book entitled _Rainbow Fish_ to most of the remaining children. She is surprisingly good at it, though the precise enunciation of her voice doesn't match the triviality of the tale.

An hour later, during which Petra, astonishingly, has played nicely although with a certain aspect of – er – _organising_ the other children but in which David has barely shifted from Castle's broad shoulder, merely listening to the stories which Gates and Beckett have taken turns in reading, they take their leave.

That, at least, is the plan.

David is quite happy to be taken wherever Castle chooses. He is still quiet and broadly unhappy, and all that he wants to do is snuggle into his father and be comforted. It's at times like this that Beckett remembers that her twins are still really very small: barely more than babies.

Petra, on the other hand, has behaved quite well all afternoon. That should have tipped off her parents that there was trouble brewing. Trouble, in this case, meaning the equivalent of Hurricanes Katrina and Sandy together, only rather more destructive and certainly louder.

"No!" she howls, on being told she needs to say goodbye to her new friends. "Not go!"

"We have to go home."

"No!" The volume means that Petra is likely audible in Toronto, and quite possibly also Texas. "Stay!"

"Time to go home, Petra," Gates says with a fearsome glare which she evidently expects to work.

"Won't!" Petra shrieks, and dashes off to cling on to an innocent piece of furniture with one hand and a new friend with the other. Unfortunately, the friend also starts to shriek, probably because of Petra's tight grip, which infects the others. Shortly, every child is shrieking, except David, who is crying. Loudly.

Beckett regards the disaster in front of her with appalled horror. Castle is fully occupied with David, and even Gates is at a loss. The three staff members are patting and consoling, which in the face of Petra's histrionics is entirely ineffectual. Almost the only good point is that Petra is still a girl, although Beckett has no confidence whatsoever that this will remain the case. Time for drastic parental measures.

" _Quiet_!" Beckett roars. Utterly astonishingly, it works. Well, it works on everyone except Petra. Beckett stalks over to her errant daughter, hunkers down next to her, and taps her ominously. "Quiet," she growls. The panther's tone is very close to the surface of her voice. Behind Beckett, the staff start clearing out the other children. Castle has retreated to the safety of the entry hall. Gates is watching with keen interest, which would have worried Beckett immensely if she had known about it.

"Won't! No! No go home!" Petra continues to protest at klaxonic volume.

"Yes, home," Beckett says calmly, with an edge of _this is the way it will be_. "You can be quiet and leave nicely, and we can come back another time, or" – she pauses – "you can be carried out of here and never come back. Only David will come back." Absolute authority is in her voice, and the growl is still underlying her firm tone.

"No fair!" Petra howls.

"Perfectly fair. Bad behaviour has consequences. Be good, and come back. Be naughty, and don't. Your choice."

Gates's eyes are sharp.

"Wanna _stay_!" but Petra is already crumbling under the sure and certain knowledge that her mother will do exactly what she has said. After all, her parents always do follow through.

"Your choice. We are going home. _Now_."

Petra lets go of the chair leg, and stands up. "Don't _wanna_ ," she weeps, but she puts a small hand into Beckett's. Gates arrives beside them and takes her other hand.

"Sorry about that," Beckett says to the staff. "She's not usually that…um. She really liked playing with the others."

"Don't worry. If you want to bring her back, that would be really good. Like I said, most people wouldn't even consider bringing their kids to play." Beckett manages a rather forced smile. "Anyways, thanks. Maybe I'll see you at another fundraiser?" Gates mostly conceals her start.

"Maybe. Thank you."

Beckett escapes without losing Petra. Though losing Petra seems a pretty good idea, right now. Beckett doesn't like being embarrassed in public, and Petra had managed that in spades – in front of Gates, who is very obviously not saying anything at all, and not-saying it very loudly.

Petra is placed in her car seat in stony silence. Beckett snaps her harness locked, casts a glance over the miserable David, still sucking his thumb, and closes the rear doors. Gates, she notices with despair, is still close by.

"I'm not sure that was a success," Beckett manages, into Gates's silence. "Thank you for arranging it, anyway."

"The children enjoyed it. I, however, was far more interested in how you dealt with the situation at the end."

Beckett cringes.

"You have been my assistant for some time now, whilst continuing to investigate homicides. Has it never occurred to you why I kept you in that position?"

Beckett says nothing. Saying _so you could torture me on a regular basis_ is a career-limiting statement.

"It was in order to expose you to a higher rank. However, I had – until today – not observed you dealing with a conflict situation. Your unorthodox team rarely argue with you, and never fight."

 _They wouldn't dare,_ Beckett thinks.

"Your daughter suffers from no such restraint. She provided me with an excellent opportunity to assess your skills in conflict resolution, and your ability to deal with situations which require" – Gates pauses – "creative solutions." She notices Castle's impatience. "I shall discuss this with you on Monday, at the precinct." She leaves. Even when she's being (relatively) pleasant, Gates's walk is more of a stalk.

Beckett flops into the passenger seat and breathes out. "Let's go home," she sighs.

"Yeah."

* * *

As soon as the twins are home they turn themselves into felines. David goes for kitten; Petra a panther. David pads straight into Beckett's lap and curls up. She is beginning to worry about this unusual lassitude, and really hopes he isn't sick. She pets his fur and coddles him gently, and then hands him over to Castle for more coddling. She has a discussion to have with Petra.

"Petra," she says, as David snuggles down and closes his eyes, safe under Castle's hands. "Come with me." Petra regards her suspiciously, in a manner very reminiscent of Beckett's own caution.

"Why?"

"I want to talk to you."

"Why?"

"No whys. Come here."

Petra examines Beckett's set face, and rapidly determines that she will be in worse trouble for not obeying than she might already be in. It appears that Petra's memory is now at least partially functional. This may, later, prove to be less than helpful. She approaches her mother.

"Why did you make such a fuss about leaving?" Beckett asks quietly, sitting on the floor, keeping a grip on Petra, and looking her firmly in the eye. Petra squirms and wriggles and tries to look away and generally does everything but answer.

"Answer me, Petra." More squirms and wriggles. It's like trying to look a wet octopus in the face, not least as Petra's face is cycling through red, pink and white. Then she changes to panther. This doesn't achieve escape, Beckett being alive to the possibility, and nor does becoming a kitten, which merely allows her to be lifted up and regarded beadily, with a hint of chill.

"Change back." The tone does not allow for any possibility of disobedience. The _only_ way to deal with Petra's manifold mischiefs and misdeeds is to enforce the message that her parents are very firmly in charge. As with any predator, the slightest hint of weakness will be fatal. There is a pause. Beckett stands up, Petra in her grip, and moves towards the stairs. Much wriggling and growling occurs, accompanied by flexing claws and a view of sharp little teeth. Beckett remains entirely unmoved. In the background, Castle fusses over David, who is still remarkably quiet and pathetic. Since this means that he isn't getting in the way, Beckett parks that worry for the moment, and takes another two steps towards the stairs.

Abruptly, Petra is human again, and gearing up for her get-out of last resort: weeping. This has never worked before and is unlikely to work now.

"Why did you make such a fuss about leaving?" Beckett asks again. Interrogating suspects isn't nearly as tough a gig as interrogating Petra, which is quite deeply unfair.

"Not leave," her terrible toddler emits. "Play more." She sniffles. Beckett is still entirely unmoved. If she were susceptible to sniffling and faked emotion, she'd never solve a single case. She sits back down with Petra.

"When I say time to go home, it's time to go."

"No."

"Yes. If you argue about it, next time we don't go at all."

"No!" Petra glares. "Nasty mama. I hate you!"

"That's a shame. I still love you. But you are being naughty, and I don't like it when you're naughty."

"Hate you!" Petra wails, despite its complete failure to provoke a reaction and its complete lack of truth.

"Petra nasty," David whimpers. "Make her stop." This is astonishingly unusual, mostly for its pathetic tone. The twins complaining about each other is astonishingly normal.

Petra whips round to – oh. Normally comments such as David's result in assault with the deadly weapon of Petra's temper, not to mention claws and teeth. This time, she dashes over to him, turns into a kitten and snuggles down beside him, patting with her tail just as she had learned from Beckett the other day.

Their parents stare at them, and then exchange a _what-the-hell_ glance.

"Davy-boy, change back for a minute," Castle wheedles, his persuasive tone belied by his worried eyes. David does, with whimpers. Castle puts a hand on his forehead. "Not hot," he says. "What's wrong, David?"

"Tired," David manages. Petra plops a paw on his leg, presumably intending to be comforting. It doesn't really work. David dissolves into fat toddler tears, which Petra patting him with her tail again doesn't mend. Castle hoists him up on to his shoulder, and rubs his back consolingly.

"There, there," he says soothingly. "Come to Daddy." David stuffs his thumb back in his mouth, and continues to cry. Petra looks confused, which sits very oddly on her kitten face.

"Petra," Beckett says on a sudden hunch, "what's wrong with David?"

Petra becomes a girl again, clearly considering her telling-off to be over. It is, in the rather greater worry over David's sorry state.

"Sad."

Well, that's not exactly informative. "What else?"

"Tummy hurt."

"How do you know?"

"Said."

"When?" Petra looks confused. Telling time isn't a two-year old's speciality. "Before lunch?"

"No."

"In the car?"

"No."

"In between lunch and the car?"

"'Es."

It's Beckett's turn to look confused. "How did he tell you?" she asks, as curiously as Castle might.

"Said." It's no more informative than the first time. Beckett gives up. She'll investigate that little byway later. Petra turns back into a cub and pads back to her brother and Castle's lap, whence Beckett follows her.

David is still crying, in a tired fashion. Beckett takes over the soothing and patting, and puts up with the whimpering in her ear. His small body is lax and heavy on her shoulder, but he still doesn't seem to have a temperature. They're not used to this. The twins are so rarely ill (apart from horrible snuffly colds occasionally) that they'd almost begun to think that the triple nature conferred immunity.

"Sore tummy, sweetheart?" she murmurs, rubbing his back gently. Petra curls up in Castle's lap and consents to staying peaceful while he pets her.

"'Es," David sobs. Beckett rubs more, and tucks him firmly against her in the hope that the semi-upright position and rubbing will help, just as it had when the twins were very small and needed burped – _oh shit._

"Castle, get a bowl and a towel!" she squawks. Castle, thankfully, understands instantly and provides both – only just in time. David is violently sick, and only Castle's speed prevents the sort of appalling mess that they would both hate cleaning up. Instead, there is a relatively easy clean up.

David, having shot his bolt, as it were, cries for a little longer and then abruptly falls asleep mid-whimper.

"Give him to me," Castle says, on his feet and leaning down. "I'll put him to bed." Since Castle is standing, which will cause least chance of David waking – not that it's likely: David sleeps soundly at the best of times, and Beckett is cynically sure that the evening maraudings are all Petra's idea – she hands her beleaguered bundle over, and looks for Petra.

Her daughter is plopped on a cushion, bright eyed, and watching proceedings. Astonishingly, she hasn't interfered.

"What wrong?"

"What _is_ wrong," Beckett automatically corrects. "David's tummy is sick."

"Poor Dav'd. I not sick," she adds, and wanders over. Beckett notices that over the last couple of weeks her walk is less of a toddle and much more balanced, and considers the value of reins for both twins, since fast running is clearly not so much on the horizon as on the doorstep.

"I _am_ not sick."

"Yes," says Petra, unanswerably. "When better?"

"Soon," her mother answers, unwilling to be definite.

Petra acquires a very dissatisfied expression. Beckett's natural scepticism asserts itself, and she wonders if Petra is dissatisfied because her playmate and twin is unhappy or because she has no-one to order around. Petra's dictatorial tendencies are pronounced.

"Nasty sick," she emits crossly. "Not" – with the _t_ sounded: something's sinking in – "fair."

Ah. Some empathy. "No, it's not fair. But he'll be better soon and then you can play. Now you can play with both of us."

At which opportune moment Castle comes back downstairs. "David's tucked up," he says quietly, "and he's not whimpering in his sleep."

"Okay. Good. We can check up on him every so often."

Petra arrives at Castle, and regards him solemnly as he sits down. Then she changes to cub, her momentary empathy entirely vanished, and bats at him. He converts himself into his own panther and, very carefully, bats back, skittering her across the floor. She growls babyishly and comes lolloping back for another go. This continues for a little while, after which she amuses herself by pouncing on his tail, which has the key attribute that it moves, and therefore provides a challenge.

Beckett watches for a few moments, then goes to check that David is okay. He proves to be sleeping peacefully, curled around a stuffed toy in exactly the way he'd usually be curled up with Petra: their feline natures still governing their sleeping positions. Of course, Beckett can hardly quibble. She sleeps curled up to Castle in any of her personalities. Onyx loves being curled into him. She lightly runs fingers across David's forehead and finds it cool, as does the careful check down under the neck of his onesie. She supposes, rather sadly, that she'll need to think about pyjamas soon, for both of them. They're getting a little big for onesies.

Remarkably late, she suddenly works out that both twins had, despite immense emotional upheavals, stayed human until they got home. She dashes down the stairs, and only realises as she hits the bottom step that blurting it out in front of Petra is a bad plan. Petra will only use it to her advantage, being at least as manipulative as any other two-year old. However, that's a distinct improvement.

"Petra," she says calmly. "Having a tantrum when you had to leave was naughty behaviour. But you stayed a girl all afternoon, which was very good. Do you think you could stay a girl all afternoon if we went to a playground with other children?"

Petra-cub considers that. This is actually very pleasing: it suggests that at some later point there might be brain involved in her reactions, as opposed to only emotions – usually anger. She nods, not convincingly.

"If you can't," Castle adds, following the thought perfectly, "then we can't go and play with other children till you think you can – and really, really mean it."

Petra puts her head on her paws and considers some more. Even in panther-cub form, her parents can see the wheels of thought turning in her small black furry head. Her ears twitch thoughtfully, her tail wriggles. There is a space of pondering silence, and then she changes back.

"Yes," she says definitively. "Can. I be girl."

Based on previous experience of Petra's ability to do exactly what she's said – usually at precisely the moment that doing what she'd said would be most troublesome – her parents are inclined to believe her.

"Okay. In that case, when David's all better, we'll ask him too. Both of you have to stay children unless you're at home or we say you can be cats."

"David do it too," Petra states. Her tone implies that David will do what she tells him. Castle and Beckett exchange a further glance that suggests that exposure to other children is an absolute necessity, or David will never get a chance to assert his own views. Even the likelihood that he will have size and bulk on Petra won't make a difference, because she'll have pushed him into second place long before that happens. That would be very undesirable, and neither adult is prepared to allow it to occur.

"We'll see," Beckett says. "Now, dinner time for you, and then bath, and you can have story time here too."

And that's what happens. After all of that, Castle carries a sleepy little Petra upstairs, settles her next to David, still cool and quiet and sleeping himself, and returns.

"Do you think they can do it?"

"I don't know. They're very small to understand and remember. Two-year olds – even three and four year olds – aren't normally known for sensible behaviour." Castle sighs. "On the other hand, they've had nearly a month of being told all the time. Something must sink in, surely? And they do want to go out and play, so there's self-interest."

"Let's hope so. All we can do is try it and really, really hope it works. It worked today. Even when she had her tantrum Petra stayed human."

"Yeah," Castle agrees, more cheerfully. "There's that." He smiles, lazily. "And now they're both sound asleep." Suddenly he's the panther, pouncing on her, careful not to use claws or weight, and mischievously licks her face. Beckett squawks and squeaks and squirms, and then becomes her own lethal black self in defence and nips at his neck. Fairly shortly, that takes the usual course.

Going to sleep earlier really doesn't seem to be happening for them.

* * *

 _Thank you to all readers and reviewers, guests and logged in._

 _Rune (guest): no more to Gates than you see, and no: the point of this AU is that there are no other shifters._


	13. Chapter 13

**Chapter 13**

"Detective Beckett," Gates intones forbiddingly, early on Monday morning. "My office, please."

Beckett cringes at the thought. She'd been hoping, fruitlessly, that Gates had forgotten any idea of talking to her about Saturday's display. She hasn't had enough coffee for this discussion. Possibly there is not enough coffee in the _world_ for this discussion. It's not fair. Beckett is a mature woman, a parent, and a top-class detective with stats to die for (and many victims have). Gates should not be able to reduce her to a cowering child with one syllable.

"I have been considering your future," Gates begins, which is _not_ reassuring. "We have not at any stage discussed your wishes regarding the future. I think that we should." This is also not at all reassuring.

"Sir," she replies, which is safely non-committal.

"Let us recap your position. You are currently a detective second-grade. Your clearance rate, with your team, is extremely high. The best in the city, in fact." Beckett gapes. She hadn't known that. Suspected, yes. But to hear it confirmed – by Gates, who _never_ praises – is jaw-dropping. "In addition, you have acted as my assistant for three years, when required. Of course, you have had much to learn in that role, and there are always matters you could handle better." That's more like the Gates she knows and fears. "You must continue to strive to improve." Gates regards Beckett with her normal cold, disapproving stare. Paradoxically, that relieves Beckett's mind.

"Why have you never sought promotion?" Gates enquires sharply.

Beckett boggles.

"You have an excellent record, you have far more experience than the minimum required, and you have all the necessary qualities. Why have you not taken the sergeant's exam already? Indeed, why did you not take it some years ago?"

Gates's tone is more accusatory than enquiring.

"I'm a detective," Beckett says, more sharply than she would normally dare. "That's what I do. I don't want to drive a desk. I want to investigate homicides."

Gates is clearly taken aback by the force of her detective's speech.

"I see," she replies slowly. "So it was a deliberate choice not to seek the supervisory ranks."

"Yes."

"I see," she says again. There is an ominous pause. "How unfortunate. I had hoped that you would wish to join them. I was intending to recommend to you that you took the Sergeants' exam – as an opening step – at the first opportunity, and that you then moved to take the Lieutenants' exam as soon as you had the necessary two years as a Sergeant. It seems that is not your desire."

Beckett emits a strangulated gurgle. Gates does not appreciate this.

"The NYPD could use people of your ability, Detective."

Beckett, despite her terror of Gates, dislikes even a minor hint of guilt-tripping.

"The NYPD _is_ using my ability. Solving murders. Getting justice for the victims and their families. Are you saying that's a waste of my time?" For once, in front of her intimidating Captain, Beckett has thrown caution to the winds and is speaking her mind freely. "Because I don't think that's a waste of my time or anyone else's. That's what I'm best at. Lots of people can be Sergeants or even Lieutenants – or Captains," she adds with an acid bite, "but the _whole reason_ my team hasn't been altered in eight years is because _no-one_ else in the city can do it as well as we do. I don't want to change that. I don't need the extra pay, if you were planning to try that line – and not just because of Castle. I never needed his money and I don't need it now. We're the best in the business at solving the weirdest murders and if you don't think that has value you're out of your mind crazy."

Gates raises a highly groomed eyebrow. Beckett stops, realises what she's just said, and gulps. That was probably a very career-limiting move.

"A very passionate statement," Gates says, in tones which imply that passionate statements should be avoided. Beckett's heart sinks, and is probably leaking out from her toes. She resists the temptation to look. "I applaud your convictions." Beckett waits for the _but_ to arrive. It doesn't.

Gates pauses. Beckett quivers in the dead silence, and says nothing at all.

"I wish you to consider carefully the possibility of a supervisory role." Beckett opens her mouth. "Do not say anything." She shuts it, quickly. She's pushed her luck so far already that it's halfway to Seattle. "Go home tonight and discuss it with Mr Castle." Gates's lips acquire their normal twist of distaste when contemplating Castle. "We shall discuss this again tomorrow."

Beckett instantly starts to hope for a lovely messy murder. In fact, _Gates's_ lovely messy murder. She wonders if Castle might _know a guy_ who could arrange it – untraceably, of course. So untraceably that even she and her team couldn't solve it.

"I am very conscious of my personal safety," Gates advises. Beckett jumps. Now Gates reads thoughts? This is _not fair_. "I advise you to improve your control of your expression. Dismissed."

Beckett staggers out. Her poker face is exceptionally good, which is why the boys never win and she and Castle are fifty/fifty. Of course, she and Castle confine their – er – more competitive games to the privacy of their loft, _after_ the twins are asleep. Others are definitely not invited to those games. How can _Gates_ read her like a book?

The day does not produce any nice messy murders to distract Beckett from her worries. She really doesn't want to stop being a detective to do management or supervisory roles. She _loves_ detecting. She does not love paperwork, or employee matters, or disciplinary processes, or bureaucracy. She goes home with a light headache and a feeling of vague unhappiness with the day.

"What's up, sweetheart?" Castle says, as she trudges in the door.

"Mama!" the twins yell, and dash over to her, grabbing a leg each when she fails to reach their level quickly enough. She wobbles.

"Let me sit down, and then you get hugs," she says to the limpets, who delimpet just enough for her to move her legs. She flops on to a large floor cushion, and is bounced on by both twins, demanding cuddles and bestowing kisses. She smiles happily and reciprocates, feeling better already. "What did you do today?"

"Playground!" they screech. "Dada go too." Well, yes. Two-year olds can hardly take themselves to the playground. She raises a querying eyebrow at Castle, and receives a smilingly satisfied nod in return. Maybe Saturday has sunk in properly. David seems to be as bouncy as usual, which is good – he'd still been a little passive on Sunday – and Petra is her normal assertive self.

"Mama come too," Petra commands. She looks at Castle, who raises his own eyebrows.

"Dinner time," she distracts. Maybe while the twins are practising the technicalities of using a spoon tidily she and Castle can sort that out. Maybe a feline trip to a playground will clear her thinking.

The children are supplied with another disguised healthy meal, spoons, admonitions to stay children, and further admonitions to eat with the spoon in their mouth. In between admonishment, Beckett and Castle conduct a coded discussion of the post-dinner activities and eventually agree that a trip to the playground as cats is a good plan.

* * *

"So what was up when you got home?" Castle asks, after the terrible twosome have been played into exhaustion and bed.

"Gates hauled me in first thing."

"Oh, dear," Castle sympathises, and snuggles her into him on the couch. "Was that about Saturday?"

"No."

He looks surprised. "No? What did she want?"

"To lecture me about not trying for promotion," Beckett replies crossly. "Told me off for not doing it years ago, and then when I said I liked being a detective told me to think very carefully and talk to you."

"Mm," Castle hums comfortably. "If you were a lieutenant, or a captain, you could make sure the twins weren't discovered." He grins.

Beckett makes a very unhappy noise.

"What's wrong?"

"I don't _want_ to be a lieutenant or a captain. I don't even want to be a sergeant, and I'd have to do that for two years minimum. I like solving homicides. I'm good at that. I hate paperwork and bureaucracy."

Castle looks at Beckett very carefully. "Really? I thought you liked it when Gates made you her assistant."

"Only because I wasn't allowed out of the precinct and it was the only way I could do anything even faintly interesting. As soon as I could go back to solving murders I did, even if she made me stay assisting too." Her face twists. "But maybe I should do it to protect the twins."

"No," he says firmly. "Definitely not. What do you want, love?" His fingers pet at her shoulder and arm, gently. She snuggles closer.

"I just want to keep on solving murders. I don't want to stop doing that."

"So don't, then. It's not like you need to be promoted. But if you were a sergeant, would you still be able to do homicide?"

"I don't know. But I'd not be out in the field nearly as much. I don't want that," she says again, her face miserable.

"Why don't you just be Onyx and not think about it," Castle suggests. "Maybe it'll be clearer tomorrow."

"Doubt it," Beckett mutters, but she turns into Onyx and pads into Castle's lap, arranging her head on her paws in a dignified posture and curling her tail neatly around herself. Castle's strong, clever hands pet and soothe and stroke, and she gradually relaxes and stops fretting, her dignified pose slipping into a dark laxity upon his lap, soft and sleepy, curling around herself, and eventually emitting a quiet, contented purr. Castle always knows just how best to soothe her.

She turns herself back into Beckett, sneaks her arms around his neck, and kisses him deeply. Castle is quick to respond to her unspoken gratitude, and it takes a little time before her mouth is free. "You always know," she murmurs. "Love you," and kisses him again, slipping his shirt open and her fingers inside. Castle's hands wander freely, until Beckett is purring again, and he's gently growling deep in his chest, and they mutually agree that this is best continued in the bedroom.

In the bedroom Castle most unfairly sneaks up behind Beckett, catches her, scoops her up and drops her on the bed, looming happily over her with a very predatory smile. She smiles back, equally predatory, and without much further ado they prey on each other, which leaves them both very satisfied indeed, and removes any possibility of fretfulness. Instead, they snuggle up together, and find peaceful sleep.

* * *

Tuesday morning, Beckett approaches the precinct with considerable trepidation. She knows that she's making the right decision for her, but that doesn't stop her worrying about it. She's barely sat down when Gates is on her, faster than a hungry shark and much more dangerous.

"My office, Detective." Beckett complies. "Now, what are your thoughts on the matters we discussed yesterday?"

"I don't want to be a sergeant, or lieutenant, or a captain," Beckett states flatly, concealing her trembling knees by careful placement of her limbs vis-à-vis Gates's desk. "I want to solve murders."

"I see," Gates says coldly. "And if I were to say that I were deeply disappointed in your lack of ambition, and that you have dropped substantially in my estimation?"

"That doesn't matter," Beckett bites, stung hard by the unfairness of the comment. "If you don't think that solving homicides is important, I _do_. And that's what I'm going to do. I'm not going to make myself unhappy just to make you happy."

There is a dead silence.

"Dismissed, Detective."

She trails out, utterly miserable, and buries herself in work, stopping occasionally to stare at the single photo of her family on her desk and wondering how she'll cope if she had to be a stay at home parent. Not well, is her answer to that. Not well at all. She'd told Gates the absolute truth and it's probably already resulting in her removal. No doubt Gates has been looking for an excuse ever since she'd admitted her genetic issue, and now she's managed to manoeuvre Beckett into providing one. She'd probably been hoping that the twins would have changed into cats at the children's home too, and then she could have thrown them all into some scientific lab for the rest of their lives.

Gloom descends around the Beckett desk, and nobody dares to break it. As the day passes, she becomes more and more miserable. Shift end approaches, and she's almost ready to resign by her own volition rather than wait for the inevitable execution.

"My office, Detective," Gates raps.

Well, here they go. She stiffens her spine and marches in.

"Shut the door."

Yes. Executions and sackings should be done in private. She preserves a cold, still face, and waits.

"Well done, Detective Beckett."

"Huh?" she gulps, inarticulately: as incapable of logical thought as Castle. Those were _not_ the words which she had expected.

"Your commentary earlier was the last piece of evidence which I needed: the ability to stand against your superiors when you believe yourself to be in the right, and to justify your position."

"What?"

"You would, I agree, be unhappy if forced to the supervisory track without a genuine desire to take that route. I have, therefore, been considering a different solution for some time. It had occurred to me that your failure to take the sergeants' exam some time ago was not due to any lack of ability, but lack of desire. You have amply proven that thesis both by the standard of your work as my assistant and your complete lack of enquiry into the possibility, despite the fact that following the birth of your children it would have provided you with a slightly more family-friendly working schedule."

Beckett growls, very slightly, at the thought that she wasn't attending to her family. Gates regards her coolly.

"You need not growl. It is not possible to doubt your care for your family, nor your devotion to both them and your job. No criticism is implied." Beckett stands her annoyance down. "As I was saying, I have been considering a different solution, and I believe I have found one."

"What is it, sir?" Beckett asks, completely confused.

Gates smiles. This is very uncommon, and quite terrifying. "I have recommended you for promotion to Detective First Grade. Your service record stands you in excellent stead. Of course, nothing is assured until the Commissioner has approved it, but I expect that it will be looked upon favourably."

Beckett simply stares at her Captain, being completely incapable of speech. Her mouth opens and closes a few times, without production of noise. Eventually she manages to close her lips for long enough to collect her thoughts.

"Thank you, sir," she almost-gasps.

"Dismissed." Gates waves her away. For the second time that day, Beckett staggers out of her office and back to her desk. The boys cast sympathetic looks at each other, assuming that Gates has been reprimanding her. It's Gates's normal behaviour, after all.

Beckett's drive home is attended by flusterment, only just enough attention to ensure she doesn't have an accident, and a complete failure to park properly until the fourth attempt. She can't concentrate on anything except Gates's quite astonishing words. _Detective First Grade_? She'd never thought – one has to be about ninety-five with fifteen medals to get that, she'd believed. It's… well… _wow_.

She stumbles in the door, to the family's amazement.

"Ma-mommy!" Petra yells. Beckett's so discombobulated she doesn't even notice that Petra's trying out Mommy for size again.

"Mama!" David attaches himself to her pants, and tugs. Beckett automatically ruffles his hair.

"Hey," Castle says, from a cushion on the floor. It looks rather like they've been out again, since the floor is largely devoid of toys. "We've only been back for half an hour. Another successful foray to the playground," he says proudly.

"Yeah," Beckett says distractedly. "That's great. Uh, can we talk?"

Castle instantly looks worried. "Sure," he says carefully. "Um, why?"

"Just… Gates is recommending me for promotion."

"But you said you didn't want to."

"Detective First Grade."

Castle's jaw drops. "That's _awesome_!" he blurts. "I thought you had to have like eighty years' service and the Congressional Medal of Honour to get that?"

Beckett just nods. Castle kisses her soundly. "That's _awesome_ ," he says again.

"Aw'sm," imitates Petra. "What happen?"

"Mommy got good news."

"Choc'late?"

"Just as good."

Petra regards him dubiously. In her toddler world, very little compares to the wonderfulness of chocolate. David bounces up.

"Choc'late?" he says hopefully, and bats his eyelashes.

"No, no chocolate. Mommy's happy."

Beckett gathers them in and hugs them very hard. Castle wraps her in and hugs too. Her eyes are a little damp, which is quite ridiculous. She can't believe Gates's action.

"Detective First Grade?" Castle says again, delightedly.

"But she made me wait all day. I thought she was going to fire me."

"Ugh," he sympathises, and cuddles her some more.

"Down, Mommy," Petra squeaks. Beckett drops a kiss on her head, and lets her go; does the same for David. Both of them bounce off, randomly changing form and chasing each other round the furniture. Beckett watches them, and then, full of happiness, changes herself into her panther and chases them too, stalking and pouncing in a way normally reserved for Castle. He follows her lead, and shortly there are four black panthers playing enthusiastically around the room.

* * *

Later that night, contentedly cuddled up to Castle in their extremely comfortable bed, the twin terrorists peacefully asleep, Beckett reflects that, all things considered, the last month has generally been very successful. Of course, her natural cynicism suggests that the twins will do something terrible very shortly, but that's a bridge to cross another day. Right now, they're co-operating. All her friends and family have adjusted to their, um, additional genetics, and she can rely on Gates to assist. In Gates's own inimitable way.

She wraps an arm round her Castle, and lays her head on his broad chest.

"You're thinking, love," he rumbles. "What're you thinking?"

"It's all going right," she says happily.

"Of course it is. We're all very cool, as cats."

 _ **Fin.**_

* * *

 _Thank you to all readers and reviewers who've come along for another sardonic ride in this crazy universe. I think we're done with the Caskett Cats, certainly for a while._

 _I am working on another story, which will appear when I've finished it (currently progressing nicely, but I make no promises on timing)._

 _Hope to see you all there. Thank you._

 _Garrae._


End file.
